Looks like Bioware is drifting to a somewhat free model come July for their Old Republic MMORPG. At that point, the game will allow people to play the game for free whenever they want, but they'll only be able to go up to level 15. So, it's pretty much the same as WoW's system of letting players futz around in low-level areas to their hearts content without paying a dime.
Of course, the question is whether this will be a slippery slope towards a full-on F2P model for the game. Unlike WoW, TOR doesn't have 10 million subscribers to profit from, and the game has been riddled with problems like lack of subscribers, relatively unpopulated servers, and there doesn't seem to be much on the horizon that will convince the unconverted to invest their time, let alone their money, in the game.