While Microsoft hasn't publicly announced such, "several sources connected to the matter" have come forward, revealing that Microsoft is weighing two options: either games that support in-game purchases, or can be upgraded (new expansions and the like) at a premium cost.
Of course, the question now remains: just which developers has Microsoft reached out to? Is it possible that we may actually see games like Zynga's FarmVille or the more hardcore focused Empires & Allies given the 360 treatment, with console specific achievements and their own marketplaces? With free-to-play, the possibilities are endless. The cost of "free" gives developers the freedom to try anything knowing that players will give it a chance simply because it costs them nothing to do so. In the world of gaming, free seems to be more and more of a good thing.
Are you excited about the idea of free-to-play games launching on the 360? Would you play games normally available on Facebook on your home consoles, with your console specific friends? Sound off in the comments.