engine - 6:24 pm on Feb 18, 2010 (gmt 0)
There's some great information on the Search Alliance site.
The Yahoo! and Microsoft Search Alliance [advertising.microsoft.com]
When the Yahoo! and Microsoft Search Alliance is implemented, both companies will continue to have differentiated consumer search experiences. However, Microsoft will manage the technology platforms that deliver the algorithmic (powered by Bing) and paid (powered by adCenter) search results.
Yahoo! and Microsoft will each provide customer support to different advertiser segments: Yahoo!ís sales team will exclusively support high volume advertisers, SEO and SEM agencies, and resellers and their clients. Microsoft will support self-service advertisers. In addition, Microsoft adCenter will be the platform for all search campaigns.