This is a significant enough move that I wanted to point out separately from Yahoo announcements below: this is the first major switch in the nascent mobile search arena: Opera, which has the popular Opera Mini browser, has dumped Google as the default search ion the Mini homepage and moved to Yahoo Search. The Google deal was about a year old.
Opera has two browsers: Opera Mini and Opera Mobile (not sure it need to keep two…is kinda confusing). Yahoo will be the exclusive search provider on these two, and will provide the new Yahoo oneSearch mobile service.
Some more details in the release here.