This is probably the best example of why I always try to put the word "rumor" into my titles when I can't verify the source of a report myself. Just check out this Google query: Emil Protalinski rumor site:zdnet.com. These articles get significantly less traffic because I warn readers in advance that this news is not solid, but as long as I control my own titles, I prefer it that way.
Anyway, back to business. First, Reuters posted an article titled "Facebook's IPO already oversubscribed: source." The introduction has everything you need to know:
Facebook Inc's record initial public offering is already oversubscribed, a source familiar with the share listing said, days after the world's largest social network embarked on a cross-country roadshow to drum up investor enthusiasm.
Despite concerns about slowing growth, a lofty valuation and signs the company is having trouble ramping up revenue from mobile advertising, institutional investors have so far indicated demand for more shares than Facebook has available, the source told Reuters.
This was soon followed by a second article posted by Bloomberg. This one is titled "Facebook IPO Said to Get Weaker-Than-Forecast Demand." Again, all you need to do is read the first two paragraphs:
Facebook Inc. (FB)'s initial public offering has so far generated lower-than-expected demand from institutional investors who are concerned about the company’s growth prospects, people with knowledge of the matter said.
Some investors expressed reluctance after Facebook said on May 9 that advertising growth hasn't kept pace with the increase in users, said the people, who asked not to be identified because the process is private. Facebook is also telling analysts that sales may not meet their most optimistic projections, two people said.
In summary, nobody really knows anything. You can pick whichever you want to believe, if it makes you feel better.
The most recent rumor says next Friday is the big day. Yes, even that is a rumor. Shares are expected to be priced on May 17, with trading beginning on May 18.