Which is the most popular social network with investors? Facebook? Nope. Twitter? Nuh-uh. MySpace? Sorry, Rupert, but News Corp. (NASDAQ:NWS) lost on that deal.

According to a recent survey by Reuters, LinkedIn is the social network that Silicon Valley's venture capitalists consider most likely to file for an IPO or be acquired. They also like these five start-ups:

  • Solyndra, a maker of solar panels.
  • Silver Spring Networks, which makes and markets smart grid technology.
  • Zynga, which develops games to be played over social networks, including YoVille! and Mafia Wars.
  • Guidewire, a developer of software for the insurance industry.
  • LiveOps, which supplies contact center software and services via cloud computing.

I'm sure these all are good companies. But aren't you at least a little surprised to see Facebook miss this list? The world's largest social network has been publicly practicing its two-step for the IPO ball. In July, the company hired a new Chief Financial Officer. Last week, it acquired FriendFeed to bolster its real-time offerings to users.

Why should LinkedIn rate higher than Facebook, when the latter site's so clearly angling for a heaping helping of the IPO pie that Open Table (NASDAQ:OPEN), Rosetta Stone (NYSE:RST), and Changyou.com (NASDAQ:CYOU) have enjoyed?

I can see two reasons. First, Google (NASDAQ:GOOG), Microsoft (NASDAQ:MSFT), and Yahoo! (NASDAQ:YHOO) have turtled when it comes to speculative social networking investments. LinkedIn leaves fewer reasons for these firms to duck and cover, because the network is 100% focused on business connections, and easier to monetize as a result.

Second, BusinessWeek's Sarah Lacy reports that Facebook's employees are continuing to cash in shares. Not exactly a sign that an IPO is in the works, nor much of a vote of confidence in the overall business plan.

Twitter, meanwhile, keeps getting hacked.

LinkedIn may hold less promise than either Twitter or Facebook, but it's probably the most stable and most predictable. In today's troubled market, investors in public and private issues prize few things more.

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