It's currently available to play @ Orbit. Personally my very limited first impressions is that the new graphics make this an absolute joy to play, a lot of new tracks and I'm hoping to get a friend to come out with me to test out the new battle mode. Check it out, for the homebound a console version will be available later in the year. Anyways, check it out, I doubt you'll be disappointed.
NOTE: This machine replaces the original DDR Extreme Machine they had
EDIT: The game is called Dancing Stage Supernova (Europe), not DDR Supernova (US), I don't think there's any difference though