I'm playing in one game of D&D4e at the moment (see the Swordlands Story hour, link in sig!).
Apart from that:
Savage Worlds - Hellfrost setting (once a week)
Warhammer 40K: Rogue Trader (mini-campaign, probably ending next week)
Shadowrun (mini-campaign, starting in a few weeks time)
D&D3.5 (about once every two months)
Mage (infrequently, but a long running campaign)
Various custom games (at a twice yearly mini-convention with friends)
Mage (again, at the Convention)
One-off unique LARP (again, at the Convention)
Esoterrorists (ran it at the convention, running it again (but better!) at GenCon this year)
Ars Magica 5th Ed (just starting on a potentially long-running game)
Dr Who (two sessions, possibly more to follow later in the year)
I would love to play in a fast-paced action-packed game, and hoping Shadowrun will scratch that itch.
Also playing Mass Effect 2 on Xbox 360, which is satisfying my space opera RPG itch.