unless I'm mistaken this will change nothing in serps, it's for the ad platforms only?
Regardless, the timing of this, it's EXCELLENT. Google just took a dump on tons of quality sites by sending them fewer visitors. The playing field being more level between search engines on the ad revenue front would be most welcome in this time of Google upheaval, hopefully it translates into more yahoo/bing search use.
edit: nothing negative towards Google was meant by that - upheaval: A sudden, violent disruption or upset. I think Mayday qualifies and I'm a Google supporter in general so it's not completely easy for me to say it like it is this time.
This isn't an acquisition or merger but what an alternative indeed! 29.5% ad market share? Do a good job and get it right Bing/Yahoo!