Valve has now made the beloved Team Fortress 2 game FREE for everyone to play. Those that don't already own it (what's wrong with you!!) can simply go out to Steam and download it without a credit card or any purchase.
For those of you that have already puchased it, Valve has detailed the difference between the free and "premium" accounts:
"Q. How is a free account different than a premium account?
Premium accounts have a few extra features, including access to rare and cosmetic items through random item drops, the ability to store more items in your backpack, and more powerful trading and crafting abilities. Otherwise, the gameplay experience will be identical for both accounts."
More details at the FAQ here:
http://www.teamfortress.com/freetoplay/faq.phpThey also created a new "Meet the Medic" video for your viewing pleasure: