It looks like Sega's not only targeting Xbox Live Arcade for another Gunstar Heroes re-release. Ratings from both the ESRB and PEGI have hinted at a possible PlayStation Network stint for the Genesis shooter.
If it does indeed show up on PSN and XBLA, I hope it has online co-op. Playing Gunstar Heroes with a friend is loads better than playing alone. Sega hasn't confirmed anything as official yet, but keep checking back here for updates.