Today I ran into a 728x90 Ads by Google Leaderboard on a Facebook page, I thought Facebook had a contextual marketing deal with MSN?

AdSense has been known to perform badly on social networking sites the same way they do on forums, it is a case of pure numbers running up millions page impressions daily, might add up to tens of millions of monthly earnings for Facebook.

But with excellent targeting information already in had, Facebook is said to be a goldmine for advertisers who can tap into the FB back end and serve ads accordingly, I just didn't expect to see AdSense there with the MSN deal. Does anyone know if Google has access to Facebook's back end? Would be a waste serving their vanilla per page contextual that we are struggling to keep targeted.

Running to invest in tinfoil now.