A New York Times article today describes many of the decisions and possible pitfalls of the various kinds of auctions Google might use. Also check out the Google SEC filing. One can learn quite a bit about auctions as well as the business of search engines from this rather informally written document. I have never had so much fun reading a prospectus.
My prediction: Great interest in Google will highly overvalue the stock whatever auction mechanism they will use. If you are interested in investing in Google, hold off until the price settles or you will suffer the dreaded "winner's curse."