"What's the catch?", you may ask. Valve is promising there's absolutely no catch. The core gameplay will be left unchanged and players will be able to enjoy Team Fortress 2 without spending a dime. If players want a fancy hat or other items in order to personalize their character, then that's where you'll be asked to spend some cash as the game will now be supported by in-game purchases.
According to Valve's Robert Walker in an interview with Develop-Online, it looks as though making Team Fortress 2 into a free-to-play product had been knocked around at Valve for quite some time. “We’ve been toying with the idea of making Team Fortress free-to-play ever since the Mann-conomy update. The data we got back from that update leads us to believe that TF2 would be more successful as a completely free product.”
Aside from Team Fortress 2 going free-to-play, a new "Meet the Medic" video has also been released. As expected, the video is full of a healthy amount of humor and even goes into the mysterious origins of the "Ubercharge" and how it works exactly.