Playing in a 4e game.
Running a 4e game and a homebrew scifi game.
My 2 roomies and I are playing through Scales of War too, with me and one of my roommates taking turns running adventures. We made level 4 characters since the xp about balances out (3 4th roughly equals 5 1st). The DM runs his character too, but has them mostly "background" until combat. So far it's worked out pretty well.
Also random pickup games that happen from time to time in various systems (1st edition Exalted, GURPS, Alternity, Star Wars, Dark Heresy, Warhammer RPG, homebrews).