Facebook's initial public offering is scheduled near the end of April 2012

 
Even before the investment from Goldman Sachs, Facebook had expected to pass 500 shareholders at some point in 2011, and therefore expects to start filing public financial reports no later than April 30, 2012. While Facebook could decide to report financial publicly without actually going public, once it goes through the trouble of financial reporting and the increased scrutiny that brings, there will be little remaining reasons to remain private. So the clock is now ticking. Expect a Facebook IPO by April, 2012.
 
An initial public offering ( IPO ), referred to simply as an "offering" or "flotation", is when a company (called the issuer) issues common stock or shares to the public for the first time. They are often issued by smaller, younger companies seeking capital to expand, but can also be done by large privately-owned companies looking to become publicly traded.
 
The SEC is concerned about the growth of the unregulated Facebook shares market. Funds are being created specifically to invest in these types of securities. Facebook will have to 'face' the SEC's 'book' before they'll get a green light. 
 
http://techcrunch.com/2011/01/21/facebook-ipo-april-2012/
http://en.wikipedia.org/wiki/Initial_public_offering