Mobile is the new battlefield, and Google has a huge lead. Yahoo! currently drives the market share of Microsoft/Yahoo! alliance, and it'll be interesting to see what effect Windows Phone 7 has on mobile search.
Coming out of the mobile search panel at SMX East, Chitika's Dan Ruby presented data showing that "Based on traffic coming through Chitika network, Google controls 97.22% of all mobile search traffic. Yahoo! is second at 1.93%, Bing 3r at 0.6%, Ask 0.23% and AOL 0.03%."
Ruby also took a look at the sources of Google's traffic from the iPhone. Here's the breakdown of Google's iPhone search traffic according to Chitika (toolbar, Google.com, app):
And, here's Chitika's comparison of traffic/share from Google App vs. all other traffic sources. According to Ruby, Bing App doesn't pass a referral URL so it's challenging to track. Hence the two Bing entries below: