That would really, really be a shame. From the article:

The original song category for the Oscars has already hit its share of clanky notes, what with none of Eddie Vedder’s breathtaking songs for “Into the Wild” making the cut. And now comes quiet word that “Falling Slowly,” the achingly pretty song from “Once” written by Glen Hansard and Marketa Irglova, may be ruled ineligible. The Bagger has been making some calls and there are indications that that the song, which is up against three, count ‘em three, songs from “Enchanted” in addition to “Raise It Up” from “August Rush,” may have some problems with eligibility requirements. Post nominations, this tempest could set the teapot to boiling. (There is a lot of seemingly well-informed speculation in the comments, so give a click for more info.)

The relevant language from the Academy rules suggests: “An original song consists of words and music, both of which are original and written specifically for the film.” (bold is theirs)

It is unclear how “Falling Slowly” may have run afoul of those rules, but the music branch of the Academy branch will be looking into the matter on Monday with a decision to follow soon after.