It is offical! Sonic Adventure on the Dreamcast will be ported to the PSN/360 around the fall time this year.
So the major changes is obviously the graphics, but since the Dreamcast did'nt support 16:9, it's going to be in the same format it was before. The addition of Leaderboards for both versions was announced, and the Sonic Adventure Internet browser will be replaced with the Leaderboards option. No more information is announced, or leaked, but it's coming, and that's what we're hoping.
Link for a video
http://media.ps3.ign.com/media/076/076867/vids_1.html
Link for images
http://media.ps3.ign.com/media/076/076867/imgs_1.html
link for story to prove that this is real
http://ps3.ign.com/objects/076/076867.html