Facebook’s public valuation is of course a moving target, given that they’re a private company, but a recent investment of US$200 million by a Russian investor for a 1.96% stake in the company puts the valuation at roughly $10 billion. Not too shabby. 2 years ago, Microsoft invested $240 million and attached a valuation of $15 billion.
What’s important here is the order of magnitude of the valuation. Facebook is of course positioning themselves for a much better valuation by continuing to grow their membership base to the point where they become more like an 8000 lb gorilla in the social networking arena and can then leverage that power to grow their capabilities beyond their current offerings.