Facebook had a relatively bad day for an IPO
Facebook came out of the gate at $38/sh and the managers of the IPO had to prop up the price by buying shares at the open to keep the price from dropping below $38. And when the market closed at end of REGULAR trading it was only at $38.23 - a VERY poor showing for a 1st day IPO. I guess all the stories all week knocking Facebook's future kept the market from driving up the price.
Here is a nice comprehensive article from Morningstar discussing the Facebook situation. Morningstar thinks a fair value for Facebook shares is $32/sh.
Advice is hold off buying for a while because the price will be dropping.