Oct. 21 (Bloomberg) -- Google Inc., Yahoo! Inc. and Microsoft Corp. are working to include Twitter Inc. messages in their search engines, giving more exposure to the social- networking service.

The companies, which lead the U.S. search market, made separate announcements today about letting users get Twitter messages, called tweets, in query results. Microsoft also plans to include Facebook Inc. messages in its Bing search engine.

Twitter, which lets people share 140-character messages, has attracted millions of users over the past year. They use the site to post everything from storm warnings to what they had for lunch. Twitter will help search-engine users get more up-to-the- minute information on query topics, said Google Vice President Marissa Mayer.

“The next time you search for something that can be aided by a real-time observation, say, snow conditions at your favorite ski resort, you’ll find tweets from other users who are there,” she said on Google’s blog.

Twitter attracted about $100 million in venture capital funding last month, valuing the company at $1 billion, according to a person familiar with the matter. The company is considering generating revenue by having advertisements on the site and giving marketers deeper access to its data, Chief Executive Officer Evan Williams said yesterday.

Little Revenue

So far, Twitter hasn’t converted its popularity into significant revenue. The San Francisco-based company had 20.9 million users in September, up about 18-fold from a year earlier, according to research firm ComScore Inc.

Google, owner of the dominant search engine, expects to showcase its Twitter features in coming months, Mayer said.

Microsoft is testing its Twitter features, Yusuf Mehdi, senior vice president at the company’s online audience business, said at the Web 2.0 conference in San Francisco. Bing will let users rank the tweets and see links from Twitter that relate to their searches.

Yahoo, based in Sunnyvale, California, also said it’s experimenting with Twitter feeds in search results. Yahoo and Microsoft struck a deal in July to join forces in the search market. The agreement is undergoing an antitrust review.

Google had 64.9 percent of the U.S. search market as of last month, according to Reston, Virginia-based ComScore. Yahoo ranked second with 18.8 percent, while Redmond, Washington-based Microsoft accounted for 9.4 percent.

Google, based in Mountain View, California, fell 62 cents to $551.10 today in Nasdaq Stock Market trading. Microsoft rose 21 cents to $26.58, while Yahoo climbed 49 cents to $17.66.

To contact the reporters on this story: Brian Womack in San Francisco at bwomack1@bloomberg.net; Dina Bass in Seattle at dbass2@bloomberg.net

Last Updated: October 21, 2009 19:00 EDT