If you guys go to the web site and see what is going on, they are celebrating Sega's 60th anniversary with a bunch of random freebies and content like wallpapers.
So on December 2, the Sonic-themed bonus will be available. It might be a downloadable soundtrack, or a wallpaper, or a free download for an old game like Sonic 1 (again). We don't know what it will be, but it's not a new game announcement.
Right now, if you sign up for access to all the freebies, which began about a week ago, you get a free copy of Saturn NiGHTS on Steam.