While some analysts still quibble over valuations and acquisitions, eMarketer has published a study that sees social networking ad revenue nearly doubling in 2008, from $1.2B to $2.2B.

MediaPost reported Monday that most of the growth will come from U.S. networks, where growth should boost revenue from $920M to $1.6B.

"The continued growth of social networking seems assured unless teens stop social networking as they become adults," said eMarketer senior analyst Debra Aho Williamson Friday.

Meanwhile, networking leaders MySpace and Facebook continue to search for methods of advertising, to diversify ad opportunities and increase inventory.

Both companies have explored behavioral targeting platforms, with Facebook hitting a speed bump over the Beacon controversy.

Privacy issues may linger, but eMarketer still sees growth in the horizon. The firm predicts the astonishing growth to slow to 16 percent by 2011 at $4.1B.