The value of huge social networking operation Facebook is a matter of endless debate among experts. The company has over 500 million members, but by most estimates will have revenue of only $1 billion to $1.5 billion this year. Management says that advertisers are flocking to the site, but how much that will bring in total sales remains to be seen.

The Financial Times reports that Facebook's value may now be over $33 billion. There is a secondary market in its shares set up by some investors and management for employees to get money for their ownership. These shares sell for as much as $76, which is how the large valuation number is derived. The Times says that Facebook must keep its number of shareholders below 500.

The rationale for Facebook's value is fairly simple. The company is still growing rapidly. Yahoo (YHOO), which is not growing, has a valuation of $18 billion. eBay's (EBAY) is $30 billion. It may not, however, be reasonable to compare a social network to an Internet portal or auction site.

The case against Facebook's valuation is that its revenue in relationship to its audience is disjointed. And, it may stay that way. Yahoo's audience can be sorted by subject so that advertisers can reach people interested in specific content -- finance, jobs, sports. eBay's content is based on detailed searches of products and sales and can be matched with the commercial interests of its visitors. Facebook is still a collection of members who cannot often be readily identified by interest. There has been some resistance by members to allow the company to "mine" data about them and share information with marketers. However, Facebook will have to do some level of data collection if it wants to continue to draw major advertisers.

In the meantime, Facebook may have an IPO in 2012, according to its CEO and founder Mark Zuckerberg. Until then, any value amount is just a guess.