Facebook formally announced on Thursday that it would team with Unity Technologies to "integrate support for the Facebook platform, including an all-new PC gaming platform currently in development."
The deal will expedite the porting of games onto the Facebook platform, providing Unity access to the over 650 million Facebook users who currently play Facebook-connected games. The creation of a Steam-like, dedicated desktop platform will allow Unity to provide Facebook users with access to games far more powerful than those currently available.
The Unity integration into Facebook would, essentially, provide users with access to more of the iOS and Android games they currently play. The desktop platform, however, would make available games that were previously only available through services like Steam or on dedicated consoles.
Facebook's obvious target here is Valve's Steam marketplace, which already has over 125 million monthly users. Facebook is hoping to lure developers to its platform by making its 650 million gamers available, and believes that, with Unity's assistance, it can make it relatively simple to port games into its new platforms.