The Once-ler happens to play the guitar and has a number of solo songs in which he picks it up and sings. Singing is very much a part of his character.I cannot express how happy this makes me. However, the only info about the movie soundtrack I can find is a score-only CD thatcomes out the Tuesday after the movie does. I sincerely hope that if nothing else, the songs will be on iTunes. (Not that the score, by John Powell, won't be awesome.)
In related news, the world premiere screening of the movie is going to be this Sunday, which is my birthday, coincidentally.
Update: There's a new character-centric featurette, and this time it's the one I was waiting for: Ed Helms talking about the Once-ler: