Ok, I don't believe a thread has been started for this yet...
It was announced yesterday that Google & Yahoo have entered into a partnership that will have Google Adwords ads displaying on Yahoo search and content networks. It's a non-exclusive agreement, and it doesn't mean that Google is buying Yahoo, but nonetheless it's an interesting move.
Google & Yahoo did a test of Google ads running on Yahoo a few weeks back while Microsoft was still pursuing them. At this point it looks like the Micro-hoo deal is officially dead. There's a lot of info and rumors flying around, of course. Right now it sounds like a good opportunity for users who aren't currently advertising on Yahoo, but I'm not sure if it will have any effect for those who advertise on both Google & Yahoo. We'll have to keep a close watch on the numbers and see how it goes!
Some linkage on the news:
As Expected, Yahoo Announces "10 Year" Google Paid Search Deal
Official Google Blog: Our agreement to provide ad technology to Yahoo!
Yahoo Announces Non-Exclusive Search Agreement With Google