Steam Community Market Enters Beta

Service expansion allows players to buy and sell in-game items via Steam
Valve has announced the launch of Steam Community Market, a new Steam functionality designed to expand the Steam Economy beyond trading. Players are now enabled to buy and sell in-game items with other players for Steam Wallet funds.
The Steam Community Market, now in beta with Valve's Team Fortress 2, will be available to other titles on Steam in the New Year. Games that participate enable users to show off their items on the Steam Community and sell or trade their items to others.