In an interview with GamesIndustry.biz, Ubisoft executive director Alain Corre offered substantial hints that the new project may be a music game. First, he described Q as "very advanced and specialised in how to exploit the music genre."
GI followed up by asking about Ubisoft's interest in entering the market and competing with Guitar Hero and the like. "We have been researching the music genre a lot," Corre said. "We know some iterations of music games are working very well in the music category. There are a lot of new things to invent in the future with voice or dance, so we're very much looking at what we can do in that respect."
This is no absolute guarantee that "Codename Eden" is some kind of music game, but the proximity of the two statements is interesting. And the prospect of a new music game from the creator of Space Channel 5 and Rez is wonderful.