Valuation aside, the parade of share lock-up expirations through the end of the year will probably keep FB down for a while. I may start looking at it if it's in the mid-low teens in late December (near the tail-end of the lock-up schedule).
Although, with the imbalanced share structure and a management team that seems to resent going/being public and has repeatedly expressed the interest in user experience over profitability, it may not be worth owning at any price.