According to Michael Arrington, an unnamed Faacebook engineer attended TechCrunch's party the other night and bragged to a group of people that Facebook "knows all about Google's social product plans". This person evidently said or implied that Facebook has obtained copies of internal Google documents that outline the company's social strategy.
This whole "Google vs. Facebook" thing may get real. As Arrington notes, neither company will comment on this, so there's no real confirmation that any of this is true. It could've just been a Facebook employee messing with people. Or maybe it's true and these companies are about to go to battle on a different level.
If it's the latter, and the cat is really out of the bag, it's surely going to have to be addressed. Some are already speculating that a lawsuit will ensue, but it's certainly early in this story to jump the gun on that.
Either way, as if Facebook didn't have enough to worry about between never-ending privacy complaints and lawsuits (frivolous or not), they may have a new problem on their hands.
Google hasn't revealed much about its social strategy outside of the products it has already released, but rumors have been rampant that the company has some things in the works aimed at rivaling Facebook. It looks like games will be a significant part of that.