Prepare to be shocked, but they don't. I mean, other than busting down the doors and taking the servers they need.
Remember that guide that was leaked a few weeks ago, detailing the procedure required for law enforcement agencies to get user info? Presumably that is not some sort of elaborate conspiracy to convince Facebook users that the government is not monitoring each and every one of their check-ins.
The FBI has free-range to do whatever it wants on Facebook. All they need to do is submit a request to the FISC which approved 100% of such requests in 2010
