Am I the only one thinking that Facebook's IPO was actually a success? The point of the IPO is to sell your company shares at the best possible price and Facebook did it.
Compare to an A/B/C round for a startup. If you know investors are willing to pay $50m for the round, but you settle for $25m, then you just lost $25m and gained nothing.
I think the main reason FB is falling now, is not because the stock was not worth $38, but everyone that expected it to quadruple overnight is now selling.