One of the interesting gems in this filing is at the very end, it details stock grants for acquisitions so you can infer the running rate of talent acquisitions. So for example, "On February 28, 2011, we issued 681,357 shares of our Class A common stock as consideration to a company in connection with our purchase of certain assets from the company." You can cross reference these with news and correlate approximate acquisition cost based on the estimate value of price per share assuming, say, a valuation of $100 billion. So I'm guessing that the company I mentioned is Octazen and assuming a $100 billion valuation (~$50 per share), this comes out to about $35 million (assuming an entirely stock acquisition - note that Facebook spent, for example, $20 million aggregate in cash on acquisitions in 2010).