Twitter will earn an estimated $25m a year from search deals with Google and Bing

"Twitter Inc. will make about $25 million from Internet-search deals with Google Inc. and Microsoft Corp. announced in October, enough to push the site into profitability, people familiar with the matter said.
A deal that made Twitter's messages searchable on Google's site will generate about $15 million, the sources said, while a similar pact with Microsoft's Bing search engine will earn Twitter about $10 million.
As a result, Twitter is expected to make a small profit in 2009 after paying operating costs of about $20 million to $25 million a year. The San Francisco firm has 105 employees, its website says."
Source: LA Times & Bloomberg News, 22nd December 2009