Check this out:

http://www.youtube.com/watch?v=vxW2yUEEZwA&feature=g-all-u

Highlights:

-New physics and graphics engine

-"Lock-On" Technology

-Free extra PLAYABLE content if you own both episodes, which is supposed to tie into Sonic CD.

-Releasing for Multiple Devices & Consoles with Online Play

Sounds great to me so far! I enjoyed the first one, and this one sounds better.