Today SEGA updated the Sonic the Hedgehog 4 website with some nice tidbits. First they have added the first image of one of the four stages in the game, Splash Hill, which looks and possibly pays homage to the Sonic the Hedgehog games of old. On the site it also says that a video is incoming.
In response to a Blog Post from earlier this week on the site, they have also added in the full track mp3 download for Act 1 the Splash Hill Zone (composed by Jun Senoue, composer of Sonic and Knuckles and others).
Definitely check out the official site for more updates and to get the track. Remember Sonic The Hedgehog 4: Episode 1 hits WiiWare this Summer.