According to "a source familiar with the IPO", Facebook, Inc plans to price its IPO at a range with a mid-point of $31.50. That would give the company a valuation around $90 billion. The final pricing is expected in about two weeks, and "people familiar with the matter" say that the company will begin pitching its stock to investors on Monday.
So far, though, this is all "source familiar with" and "people familiar with", without any official announcement. Take it all with a grain of salt, until the actual announcement happens.