Mary Robinette Kowal's novella "Water to Wine" was originally published in November 2010 in METAtropolis: Cascadiopolis as audio-fiction. In 2011 it was reprinted on Subterranean Online. Mary's note before the story mentions that it was revised / adapted for print (removing stage directions and adding detail that works better in print than being read aloud).
Do you think it's Hugo eligible this year? I hope so, because I think the story is all sorts of fantastic and I would love to nominate it (and tell others to nominate it as well). I just don't want to waste the slot on an excellent but ineligible story.
Well, I don't have a definite answer to this. It might be eligible, if the Administrator were to rule that the revisions were sufficient to make it a new work. Unfortunately, the Administrators are loathe to make rulings without a specific case before them. That means that they probably won't tell you in advance, and they won't rule at all unless the work receives enough nominations to appear on the short list.
So my advice to you is that if you think this work is one of the five best of the year, you should nominate it, knowing that there is a possibility that it might be disqualified on technical grounds. If you think it's a worthy work, you're not "wasting" your nomination in my opinion, any more than voting for a candidate you don't expect to win is a "wasted" vote. As an informed voter, you should vote for the things/people you want to win, not think that you have to "back the winning team."
Disclaimer: I'm a former Hugo Administrator, not a current one. While I have positions of responsibility with WSFS, I do not determine policy for the administration of the 2012 Hugo Awards, and thus my opinions here are solely my own and do not reflect those of WSFS, Chicon 7, or the 2012 Hugo Award Administration Subcommittee.