New investment in Twitter values it at $3.7bn

"Twitter has raised $200m (£129m) in new finance, in a deal that values the social networking service at $3.7bn.
It said the investment had come from venture capital firm Kleiner Perkins Caufield Byers, and existing investors.
Twitter is also adding two new board members, including David Rosenblatt, boss of digital advertising group DoubleClick.
[...]
It has 175 million registered users and 300 employees."
Source:  BBC News, 15th December 2010