Via Sonic City Blognik:
Looks like Project Needlemouse isn't the only Dreamcast-anniversary-related bit out of SEGA. The official Sonic Blog released a retrospective on 9-9-09 of all the innovations and changes that the original Sonic Adventure introduced to the Sonic The Hedgehog game series.

A small snippet from the news post:

# All the characters received height/proportion edits
# Amy - completely redesigned.
# Dr. Eggman - completely redesigned.
# Eggman/Robotnik name issue resolved in dialogue - IT WAS RESOLVED I SAY.
# Cutscenes
# Full voice actor cast.
# E-100 series of robots - much more advanced enemies and of course E-102 Gamma

Full story: 10 Years of Sonic Adventure - So, What Did It Originate?