Someone named "Xbox360 Leaker" dropped a screenshot of a French-language Xbox Live Marketplace that shows the Dreamcast classic Jet Set Radio available as a demo. The picture, of unknown provenance, adds weight to rumors that other Dreamcast classics are inbound.
Jet Set Radio was the game's Japanese name (Jet Grind Radio was its name in North America), but one would have to figure that if they're going to take it this far, this game would include the additional content from Jet Grind and De La Jet Set Radio
Nothing's confirmed, but it should definitely whet the appetites of Dreamcast fans, of which there are many.
Rumor: Jet Set Radio Might be Coming to Xbox LIVE Arcade [Destructoid via Gay Gamer]