Facebook today announced that Digital Sky Technologies, has made a $200 million investment in Facebook in exchange for preferred stock, representing a 1.96% equity stake at a $10 billion valuation. The $10 billion does not refer to common stock though. The valuation of Facebook common stock is still unkown.

Digital Sky Technologies has indicated that it is planning to offer to purchase at least $100 million of Facebook common stock from existing common stockholders that would facilitate liquidity for current and former employees’ vested shares in the company. The details of the plan are expected to be announced to eligible participants during the summer.
Via this Facebook announcement.