Whoever said money can't buy friends? It certainly wasn't Facebook co-founder and CEO Mark Zuckerberg, whose company today filed for its initial public offering with the United States Securities and Exchange Commission. According to the filing, Facebook seeks to raise $5 billion if and when the company goes public -- the filing is still pending approval from the SEC.

Also revealed in the filing was news that the social platforms biggest game developer, Zynga, accounts for "approximately 12 percent" of Facebook's revenue. Zynga had its own IPO late last year, which sought to raise $1 billion in going public.

That 12 percent is enough to have Zuckerberg and co. worried about going public, as the filing notes, "If the use of Zynga games on our Platform declines, if Zynga launches games on or migrates games to competing platforms, or if we fail to maintain good relations with Zynga, we may lose Zynga as a significant Platform developer and our financial results may be adversely affected." So, uh, here's hoping Google+ doesn't get into games, eh?

... oh, right.