There's been a lot of news lately about
MSN and Yahoo. In Feb MSN offered Yahoo nearly $45M, an unsolicated buyout offer that was rejected by the board of directors.
Why would Yahoo decline such a lucrative offer? I think it's due to the founders' negative feelings about Microsoft, stemming from the 80's when Microsoft was an industry bully.
Today, many feel Google is the neighborhood bully.
Advertisers and website owners desperately need a competitor to challenge Google's hold on search engine traffic. They own ~60% of the search traffic and if you don't play by their rules, you don't play.
Unfortunately the rules are ambigious, enforced at Google's discretion and providing little recourse for the little guy.