A demo for SEGA Superstars Tennis has hit the XBOX Live Marketplace today. The free demo weighs in at 627MB. Here's the dashboard description:
Take a trip to Planet Superstars and play some crazy tennis with SEGA's greatest heroes! SEGA Superstars Tennis, a game that brings together some of the most treasured and well known characters from the SEGA universe, in some of the most unusual courts and outrageous settings ever imagined.
The demo lets players play a 5-minute match as Shadow and/or AiAi.