Steam has added Facebook to expand the social networking portion of their frontend. Features include: importing friends you know on Facebook into your Steam friends list and adding additional profile information brought in from the most popular social network onto your Steam profile. Presumably it will also allow achievement progress and purchase information to be posted to your Facebook profile, similar to how the Playstation Network connects to your Facebook profile to inform your friends of trophies you’ve earned, and purchases made on the Playstation Store. This could add an interesting layer, as it’s free advertising for the games by saying “Hey, I got this game! You might want to as well!”.
This merger is rumored to be the start of Valve's attempts at expanding the social aspects of Steam's functionality. What will this mean for Steam’s users in the future? Will Steam start to support Facebook-based games, or perhaps vice versa? Many other games are currently connected to Facebook and Twitter independently, so perhaps this connection will allow developers more options and avenues rather than working directly with a Facebook SDK. Hopefully, we won’t see our walls cluttered with people offering us free Steam games in return for our credit card numbers, social security numbers, or worse, Team Fortress 2 hats. Come to think of it, I wonder if they'll be making a Team Fortress hat for this...?