Valve announced today, alongside the ?ber Update, that Team Fortress 2 is now a Free to Play title. This means that if you don't already own the game, you can download and play it in its entirety, for free, from Steam. FOR-EV-ER.
Special or rare Items sold at the Mann Co. store, such as some of the hats and weapons, will be where Valve makes their dough from here on out -- You won't find any premium subscription services in this game.
Develop has posted a lengthy interview with Robin Walker where he explains this move. To put it bluntly, Walker said "The data we got back from [the Mann Co.] update leads us to believe that TF2 would be more successful as a completely free product."
Click here for the press notes.
More information on Free to Play is here, and you can find info on today's ?ber Update here.