Microsoft acquired TellMe back in March 2007, and the speech recognition features that came with it have been finding their way into a number of Microsoft products, from Windows 7 to the Bing for Mobile app, and soon, of course, to Windows Phone 7.
Speech recognition is deeply integrated into Windows Phone, accessible just by pressing and holding the Start key. Once speech recognition is turned on, you can do everything from look up and dial a contact’s phone number, to search with Bing, to start an app installed on the phone. Here’s a short video demo:
(Source: Microsoft News Center TellMe Press Room)