Yahoo! figures it outJun 10 2006
When early versions of Internet Explorer 7 were released, it was clear that IE would now have a search toolbar like Firefox. It was also clear that this would default to use MSN, rather than the Firefox default of Google. Google freaked out and tried to sue Microsoft, but the Justice Department said it was OK and prevented Google from doing anything about it. Google's strategy was to continue to promote Firefox, as well as give instructions to IE 7 users on how to change their default search engine.
Now, Yahoo! has released a customized version of IE 7 beta which presets the homepage and search bar to Yahoo!. Rather than fight the beast, they've embraced it and made things even easier for people who still prefer Internet Explorer. Good move, Yahoo!.
Disclaimer: I only use Internet Explorer for testing. Firefox is definitely the way to go for day-to-day surfing.