Google has fired off a very public and very snarky shot in its war against Facebook. When Facebook users try to import their contacts from Gmail, they get a little alert message titled "Trap my contacts now." Google warns, "Hold on a second. Are you super sure you want to import your contact information for your friends into a service that won't let you get it out?" Google calls this a "public service announcement" about "data protectionism." Why is Google giving Facebook the mean girl treatment? Because Facebook won't share.

"Facebook has long insisted that other sites should make it easy for their users to transfer data to their social networking profiles," Slate's Farhad Manjoo explains. "But Facebook isn't big on reciprocity. Using both technical and legal maneuvers, Facebook unilaterally decides what data you can remove from the site, and where you're allowed to take it. Facebook, in other words, is a roach motel for your social graph—your data checks in, but unless Mark Zuckerberg approves, it can never leave." Facebook found a way around Google's requirement that sites using its export feature reciprocate.

Google is framing this battle as one over users' control of their own data. But the struggle is actually about the sites' control of your data. Google allowed users to take their info to Facebook for years, but now that the search giant readying a social networking site of its own, it's cracking down.