Be warned: the Facebook IPO is a big enough event in the technology world that scammers will just have to take advantage. There is so much hype surrounding the Facebook IPO it's inevitable that malicious groups and individuals will want to cash in. Furthermore, Facebook users seem to eat up scams about Facebook itself more than anything else.
The last time I saw this big of an event abused, was the death of the Apple CEO Steve Jobs. There were various Steve Jobs scams on Facebook, and they easily overshadowed the actual news about Jobs and Facebook.
I expect the same thing to happen again, but worse. There are going to be the usual scams that just want you to click on links and show you advertisements instead of whatever Facebook IPO news you think you're going to see, but there's also going to be a lot of fraud. I believe that many are going to try to sell bogus Facebook pre-IPO stock, or claim to have free Facebook stock to give away. What better place to push such nonsense than on Facebook itself?
I've said it before and I'll say it again: don't click on everything your Facebook friends share on the social network. In general, don't believe everything you read on the Internet, especially if it wants you to click on it. Last but not least, don't buy into the hype!