In response to recent controversy surrounding Steam’s ability to allow users to trade in-game items and the use of that functionality by third-party sites for gambling, Valve has announced it will begin asking these sites to "cease operations through Steam" and effectively ban item gambling on the service.
The full statement from Valve explains that the company has "no business relationship with any of these sites" and has never received revenue from them.
Valve’s Erik Johnson issued the following statement concerning the company’s decision, explaining how the sites are violating Steam’s user agreements:
"In 2011, we added a feature to Steam that enabled users to trade in-game items as a way to make it easier for people to get the items they wanted in games featuring in-game economies.
Source: IGN PC Articles