Mark, can you post the URL, my link didn't work?

I thought it was totally sound advice, and accurate regarding the pride of place the pipe organ enjoys, but not at the total suppression of "alias instrumentus aptus." ;=) I don't think padre was portraying an "anything goes" ethos when defending authentic inculturation in practice globally.
I've heard way too many polemicists weigh in on unaccompanied chant being a rubrical imperative to comment upon the good father's admonition to sing it a capella 24/7.

Mark, it's okay to be irked. We live in an era where there is an infinite "world of possibilities."
When I first listened to the radio exchange, the dad briefly mentioned "polka Masses," and, of course, the good padre did not consign the accordian to the liturgical dunghill, which elicited a chuckle. But if one thinks it through the prism of "possibilities" is not the instrument itself, but the musical styles with which it is commonly associated, namely polka or mariachi/conjunto. The instrument is physically not unlike a pipe organ, and does, in fact, comport with the human voice quite well as a true reed instrument. But, it's easy to get passed "guilt by association" and not so easy to find a player with the skill set and chutzpah to employ an accordian at a normative OF service.
So let's move to another instrument, whose very origins lie in the muddiest and bawdiest environs imaginable: the banjo. And for argument's sake, let's say that we've all evolved way past "hootenanny music" and "Blest Be the Lord" or the Bluegrass Missa (there is one, it's, uh, ..... there....) we all agree that the banjo, de facto, cannot possibly be disassociated from its very physical nature and its vaudeville/blues/bordello/ragtime jazz roots. But some wiseacre out there says, "Have you ever heard Bela Fleck play the Art of the Fugue on his banjo?"
With the sole exception of the kazoo and vuvuzuela, I think we'll always find the exception to the rule if we argue the instrument instead of the art form, though I've grudgingly come to accept the clarinet and saxophone simply because I've had "genius" level players in my ensembles over the years. (I mean: think of Jan Garbarek and the Sixteen collaborations: who knew?)
But, now that we're clearly re-constituting our founding principles and practices, our task as Directors is too adhere to the ideal and advance that in real time, in real worship at every opportunity. That doesn't mean we turn away the mandolin player who, out of nowhere, volunteers. We just figure out how to employ those skills at non-liturgical events such as devotions or concerts.
The acid test for all instruments, as the good father said on the radio, does the use of the instrument complement or impede the beautifully sung texts of the priest, choir and congregation?

http://www.youtube.com/watch?v=v7DhL9MMVCw

Well, the good Father doesn't have all of his facts straight (getting the date right, but not seeming to remember the title Musicam Sacram), but I think he gave a pretty reasonable answer on the spot given that he is a priest and not an expert on sacred music. The organ is not given "pride of place" (a phrase he must have encountered when reading about Gregorian chant), but it is an instrument that is held in "high esteem" as the traditional instrument of the Latin Church. He is correct that the accordion itself is not specifically prohibited, although he does not mention what would be necessary for the instrument to be made suitable for use in worship.

One wonders if he is not aware of the reason he so often hears what he refers to as the "Requiem" chants sung at English Masses. The "minimum repertoire of Gregorian chant" contained in the Jubilate Deo booklet does contain the Sanctus and Agnus from the Mass for the Dead, chant which have also been specified for use on weekdays in Advent and Lent in the Graduale Romanum. They are not limited to use at funerals, and in fact the new English Sacramentary chants are based on these same melodies. The Kyrie that one hears most often, i.e. the one from Jubilate Deo, is not the traditional Requiem Kyrie, but is taken from Mass XVI (for weekdays).

dad29 cited a reason above: the piano is a percussion instrument that isn't analogous to the human voice.

Classical-era piano literature is generally secular music with the piano as a domestic instrument, while the use of piano in church seems to be (historically) a low-church Protestant phenomenon. On the other hand, much organ literature can be performed on even an electronic organ, with a more appropriate sound than that of a real piano.

If you can't sing well without a piano, you probably can't sing well with one either.

Also, introducing music that requires piano or guitar accompaniment (the use of organ to accompany chant does not fall in this category) does much to harm the congregation's musical skill as well as to keep them from developing a common repertoire. Don't believe me? Try singing "Here I Am Lord" as written without accompaniment. Compare the result to, say, Adoro te devote.

At the caller's parish, they would probably do well to make sure at least some of the choir and congregation's music is done without a piano, either chant or composed music in parts. This would do a lot to help them sing "on key" as the reverend father put it.

Also, introducing music that requires piano or guitar accompaniment (the use of organ to accompany chant does not fall in this category) does much to harm the congregation's musical skill as well as to keep them from developing a common repertoire. Don't believe me? Try singing "Here I Am Lord" as written without accompaniment. Compare the result to, say, Adoro te devote.

My dear incantu, I don't usually want to tangle with you, but "Don't believe me?" with your examples are a false positive proof. I could do both of those with ease. Trust me. With a full congregation, not just me or my posse. Ask around if you want.
I would be interested in a scientific, empirical proof to your contention of "does much harm." Seems enthusiastic, but hardly convincing given the realities of plucked string instruments and vocal music from Davidic times to the present. I mean, there's a tad of hyperbole in your contention, oui?

Developing a common repertoire, incantu? And here I always thought we're both trying to work away from Here I am Lord/ Mass of Creation... ;-) I'll take a real piano over the Hamonds I've subbed on anytime.

I'm sorry. I built tracker pipe organs for almost 30 year, and playing in Catholic churches all that time. I definitely WILL take a Hammond over a piano, any day. I will NOT, EVER, play on a piano in a church.

I showed up at one church in the Houston metro area once at the end of a Spanish Mass, with their musician pounding away on the grand piano in front. He did not know where the key to the balcony was for the next Mass (the one I was to play for). He said I might just have to use the piano. I told him they could have a said Mass, or sing by themselves, or whatever, but I would not be there. Some one DID find the key to the balcony.

I'm with Steve...accepting a piano over a hammond is wrong.

Well, I am working on my NPM certificate in liturgical autoharp.

In response to Ghmus7's observation,
Art song was originally in the category of parlor/chamber music. Some great stuff, esp the Scubert rep, but not a style that jives with sacred music 95% of the time.
I chime in as a singer who has a ton of art song recordings, appreciates the recital format, and respects (and sings) the genre as
a whole. Its good stuff, simply distinct from liturgical music. Also consider that the vast majority of this rep is for a soloist, not your average cantor, and certainly not a choir.
To recap-
M, B, and S wrote choral music with orchestral and organ accomp. Piano was associated with chamber or parlor music.

"how one can sustain a large congregation through five beats of rest without accompaniment."

Exactly, since the melodies are not written with harmonic rhythm in them and rely totally upon accompanying chord rhythms.

Because sometimes providence just doesn't provide us a pipe organ or the Tallis Scholars

Exactly. This is why I advocate a foundational repertoire that doesn't require those things.

My dear incantu, I don't usually want to tangle with you, but "Don't believe me?" with your examples are a false positive proof. I could do both of those with ease. Trust me. With a full congregation, not just me or my posse. Ask around if you want.

In my original statement which you challenged, I clearly wrote "as written." Now you suggest that that the rhythms might just "disappear." That is not singing as written. I've played for a number of congregations who have obviously done just what you suggest, and then when accompaniment is available (or a choral to sing a choral arrangement), the thing falls apart because people haven't learned it correctly. This is not what I would call "singing well." As far as just doing the best you can with what's available, I guess we'll have to agree to disagree. We might not sing for the sake of art, but we sing art for our sake, and for the sake of the liturgy. If it's not art, it's not worth singing (or worthy of the temple) -- especially when, by making better choices, art would be perfectly possible to create.

I stand corrected; I often skim pass such "qualifiers" that you did state, incantu. Apologies. I'm still not sure that in real practice of learning and rendering tunes "correctly" things are as cut and dried as you suggest. I tend to think that a congregation, when led by a truly competent organist, choir or song leader (a "song whisperer?") can still manage to sing anything successfully. I'm really not antagonistic toward your positions all. I am never comfortable with the "notion" that global, one size fits all solutions or one magic bullet solves divergent problems in our domains.