Bing search
Bing offers Wikipedia search
Bing.com, the Microsoft search engine, is offering "Bing Reference", a way to search "enhanced Wikipedia articles" (available under "more" from the main page of Bing). The "Reference" page initially displays a Wikipedia article corresponding to the search engine's daily wallpaper. From the reference page, users can then search pages from Wikipedia and from Freebase, which is a large collaborative knowledge base.