its a silent auction.
theres an extremely thorough article on google and the ipo in today's wall street journal if anyone is interested enough to pick up a copy. has previously unkown details of the company and its financials.
bottom line is that this kind of auction is pretty rare, and unprecented for an IPO of this size (which is the largest tech IPO ever, and 15th largest IPO period).
pretty much every investment bank advised against it, obviously because if this catches on it seriously threatens their wealth and power.