Paul Graham's Letter to YC Companies
Note incidentally that I'm talking about the performance of the IPO, not the performance of Facebook itself.  I think Facebook as a company is in a strong position.  The problem is simply that Mr. Market (<a href="http://en.wikipedia.org/wiki/The_Intelligent_Investor" rel="nofollow">http://en.wikipedia.org/wiki/The_Intelligent_Investor</a>) doesn't think so at the moment.