According to a report on IGN, Microsoft will next year be making free to play titles available on Xbox Live. You know, the ones that like to take $US5-10 of your money a month in tiny chunks instead of $US60 all at once.
So think Lord of the Rings Online. Or Battlefield Heroes. Those kind of games. Not necessarily those games specifically, but those kind of games. The kind of games where you can download and start playing for free, but where you'll find you'll eventually need to start paying money on a semi-regular basis to remain competitive.
Since Microsoft already has its talons in your credit card details, the kind of constant microtransactions these games survive on shouldn't be too difficult for Xbox Live to handle.
Should be good for people who like to game on the cheap and for publishers like EA who have recently bet big on the model, but as someone who disdains this payment concept on a fundamental level, it'd be nice to see it on as few platforms as possible.