Microsoft announced they have a deal with Firefox to create a flavor of their browser with Bing as the default search provider.
So today we're teaming with Mozilla to release Firefox with Bing, a version of the popular Web browser that includes default search settings for Bing. Now Firefox users who are Bing enthusiasts can use Firefox with Bing to use the Web the way they want without having to take extra steps to navigate or customize their settings to Bing.
Firefox with Bing offers the latest version of Firefox with Bing set as your home page and the default setting in the search box and AwesomeBar (where you can also type in queries as well as Web addresses). If you already have the latest version of Firefox, then you just need to download the Bing Search for Firefox Add-on to set the same preferences.
You can download it over at firefoxwithbing.com.
A Webmasterworld thread, the community there is extremely Bing positive, has comments like "Yey! Go Microsoft!"
Forum discussion at Webmasterworld.