Penny Arcade is setting up their own digital distribution system, Greenhouse, together with Hothead Games. This will be used to distribute PA's game "On the Rain-Slick Precipice of Darkness" (which is coming out for the Mac, yay), as well as... other games. They're not saying much for now. Probably because they don't know yet.
According to this interview over at Wired it was just a logical extrapolation of the way they do things. They control the distribution of their comic, so why not of their game?
No mention anywhere of that other indie game digital distributor, Manifesto Games.
(Via Boing Boing.)