The Team Fortress 2 hat economy is in full swing, with players bartering, backstabbing and frantically crafting their way to the best items. The carnage is about to spread beyond TF2. The TF2 blog announces that the Steam trading beta is now live, and will let you swap Team Fortress 2 items for unredeemed gift games on Steam.

One of the pleasant side effects of the enormous Steam sales is that you'll often buy a bundle that contains a copy of a game you already own. Most of the time you're able to gift this spare game to anyone with a Steam account. The Steam trading beta now lets you exchange a Team Fortress 2 item, say, a tower of hats, for one of those spares.

If you want, you can also buy a new game purely for the purpose of trading. As long as you don't add the game to your Steam library, it's swappable, and this is just the beginning. The trading system looks set to items in other games as well.

The wording on the Team Fortress 2 blog post states that "Steam Trading Beta lets you securely trade your in-game items for other in-game items from participating games." That suggests we might eventually be able to trade TF2 items for Portal 2 items, or even in-game items from third party games that opt into the trading system.

You can opt into the beta by selecting "Steam Settings" in the Steam menu, then picking the trading beta from the drop-down menu. For more information, check out Valve's Steam trading beta FAQ . We've tried it out. Here's how it works.