Sonic's apparently too fast for whoever moderates Xbox.com content. A listing for Sonic Adventure 2 has appeared on the official Xbox site, complete with a handful of screenshots (one with some PlayStation buttons!) and a description. The listing was pulled from the US Xbox.com, though the UK version has yet to be taken down. No downloads are available but, given that the port doesn't even officially exist yet, that's not surprising.
The listing claims the game features all of Sonic Adventure 2's original content, Chao Gardens and all, now in high definition. Given Sega has already re-released the original Sonic Adventure, it only makes sense that the sequel would be as well. We've contacted Sega to learn more.