More evidence of artificial support, a tweet and screen capture from Paul Kedrosky:

http://lockerz.com/s/209964861

It's easy to overlook the graphic; it's the thin black bar with faint text. It shows:

  Bid (size): 38.00 (x9999900)     Ask (size): 38.01 (x146300)

...and the tweet referencing it was about 20mins before the close. The earlier tweet was:

@pkedrosky: Watching certain underwriters try to keep certain IPOs above their issue price reminds me of playing Missile Commander, at scale.

Still, this isn't necessarily a negative for Facebook. They optimized their take, and Zuckerberg won't be needing the market's approval or capital again for a while.