http://www.sega.com/sonicunleashed/notw/us/

In an effort to build up hype for Sonic Unleashed (Winter 2008 in North America), Sega is making a short animated movie that appears will be released closer to the release of the game. A preview trailer can be seen on the site linked to above.

Maybe this will tie into why the werehog transformation takes places in Unleashed?