SEGA released a teaser video a few days back and have now just confirmed that this is real thing that is happening. Jet Set Radio (Jet Grind Radio in Japan) which was a Dreamcast exclusive (up until they stopped making consoles) when it first came out is getting up-res'd in HD and will be available on both XBLA and PSN (or by it's new name "SEN") as well as Windows PC this summer.
I've always wanted to play this but I never got to own a Dreamcast (or any SEGA console for that matter) I missed out. The second game, Jet Set Radio Future, was released on the original Xbox so I also missed out on that so I'm very glad that SEGA is giving the series some love and re-releasing the first game in HD.
Screenshots from SEGA: