Steam just announced they’re adding Free to Play (F2P) games on their service. It seems some of them or even all of them will be using the Steam micro-transaction backend to handle all the transactions for in-game content. Think TF2 hats.
Available immediately, the launch titles are Spiral Knights, Forsaken Worlds, Champions Online: Free for All, Global Agenda: Free Agent, and Alliance of Valliant Arms (AVA).
Starting tomorrow they’re going to run a F2P game of the day promo. If you try out the F2P game of the day you’ll get some exclusive in-game content. Tomorrow’s game of the day is going to be Spiral Knights.