Here's some videos showing the android dreamcast emulator running on a galaxy s. It is looking *very* promising. The games featured are: Crazy Taxi, Dead or Alive, and Shenmue.

http://www.youtube.com/watch?v=I5-kV_TRNyg
http://www.youtube.com/watch?v=LA0st_-RcLU
http://www.youtube.com/watch?v=3NuUVn1QRfc

This is great news. The games, while slow would likely be very playable with frame dropping. I expect the emulation to improve, though currently it's looking very good.