Below is a quick overview of Yahoo! and it’s Search History, so you can see that they have in the past used Google.
In May of 1998, Yahoo! Web Search is powered by Inktomi
In June of 2000, Yahoo! Web Search powered by Google
In March of 2003, Yahoo! Acquires Inktomi
In February of 2004 Yahoo! Web Search powered by Yahoo!
In March of 2004 AltaVista switches to Yahoo! Search
In August of 2004 Yahoo! Launches Local Search Engine
On August 18th 2010 Yahoo switches to BING
Yahoo! Organic Results Switch To Bing (Aug 18th, 2010)
http://blog.searchenginewatch.com/100824-172703
Yahoo Outsource Search to Google! Today WSJ
http://blog.searchenginewatch.com/blog/080119-165300
Yahoo Layoffs Confirmed (Monday Jan 21st 2008)
http://blog.searchenginewatch.com/blog/080120-112309
Yahoo Layoffs Updated (Tuesday Jan 22nd 2008)
http://blog.searchenginewatch.com/blog/080121-2344
Gerard Manning is the owner of Manning Search Marketing and has been working in the SEO industry since 2000. Originally started with Enquiro Search Solutions (now known as Mediative). Was previously a Research Assistant on Inside the Mind of the Searcher that was released in 2005.