The smart money values Farmville $1Bn Over Twitter...

It's often difficult to put a value on private companies because their financial data is private. But you can get some sense of their value by tracking the buying and selling of private company shares in a private market, and that's what SharesPost does.

The company announced its first value index today comprised of seven leading venture backed private companies.

The private market is interesting. It doesn't have the liquidity of a public market but it can provide a lot of rich information. This is where very wealthy individuals trade shares in venture-backed companies. It's where the smart money wheels and deals.

But it's sometimes surprising what the smart money values.

- Zynga, the maker of the Facebook game Farmville, has a $2.61 billion valuation in the private market.

- Twitter has a $1.44 billion valuation. The smart money sees $1.17 billion more value in Facebook games than it does in Twitter. Maybe it's not surprising: Zynga has revenues, Twitter does not.

- According to the SharesPost, Facebook has a valuation of $11.52 billion. That's a lot less than the $15 billion valuation it had in October, 2007 when Microsoft purchased a 1.6% share for $240 million.

That is a 23 percent devaluation, despite the massive growth at Facebook since Microsoft's investment. The smart money says that you can buy Facebook today for less than Microsoft did in 2007. Facebook today has 400 million active users. That seems like a bargain.

Here is the complete list of the companies in the SharesPost Index and their current valuation:

Facebook $11.52 billion.

Zynga - $2.61 billion.

Twitter - $1.44 billion.

Linden Lab (Second Life) - $383 million.

LinkedIn - $1.3 billion.

Tesla Motors - $1.28 billion.

Serious Materials (Cleantech) - $227 million.