The Steam Trading beta began with Team Fortress 2 items and game gifts. Today Spiral Knights, the cooperative adventure from Three Rings and Sega, and Portal 2 join the Steam economy as Steam Trading becomes available to everyone.

"The addition of Steam Trading is the latest example of how Steam continues to evolve with new features and functions developed based upon feedback," said Jason Holtman, director of business development. "We look forward to seeing how gamers and developers have fun and move this functionality forward."

During the four week beta, over 1 million items and game gifts were traded. Support for Steam Trading has been added to the Steamworks SDK.