At San Diego Comic-Con today, Sega abandoned all pretense of a surprise announcement—which is good, because this leaked a month ago—and confirmed that a port of Sonic Adventure 2 would be arriving this fall on Xbox Live Arcade and PlayStation Network.

Joystiq points out that the game briefly had a listing on the Xbox Live Marketplace, quickly removed. That's plainly what is meant when the video says "from the masters of secrecy," and then everyone freaks the hell out at the revelation of the obvious anyway.

Sonic Adventure 2 coming to PSN/XBLA this fall [Joystiq]