With the tremendous success Google has had with its AdSense and Adwords advertisement programs (likely you have heard of them if you are a webmaster), it doesn't come as much of a surprise that Yahoo wants to buy Overture
, one of the biggest players in the PPC business, which had already partnered with Yahoo but now will become one company.
[COLOR=royalblue]Yahoo said that joining forces with Overture, a company that pioneered commercial search services, will create "the largest global player in the rapidly growing Internet advertising sector." The acquisition will also help Yahoo compete with rival search engine Google Inc.[/COLOR]
You might remember Yahoo also bought Inktomi a while ago, in the long term I would expect them to drop Google search results in favor of those from Inktomi.