I think that Facebook filed for IPO a little too late. If I were the Facebook founder and I wanted to go for IPO, I would have done it at Facebook's rise in popularity. Because they were raking in more than half a billion. So, now, I think Facebook needs to convince investors that Facebook is a viable business in the long term, and excite them for the year or two to come. Facebook needs to come up with an idea that has that "I want to invest more!" feeling. Facebook needs to start offering something more than just a social network, something more than just a search engine, something more than this, and that. Because in the next few years, that millions and billions of accounts will hit a ceiling.
Here's the thing, Google didn't stop at providing a search engine, it acquired blogging solutions because it helps push their search engine business, it acquired RSS feed technologies such as feedburner to break into the RSS feed market, they acquired piscea (whatever it's called), and built their photo service, which evolved into the Google+ ecosystem. All of this piece together like a puzzle for Google.
Facebook lost sight of what the big picture looks like financially. You can't survive just solely on ads on your own service, you need more revenue streams.