Google, which enjoys 68 percent of web search share in the US and 87 percent in the UK, already dominates over 61 percent of mobile search, says Nielsen Mobile (via InformationWeek).

Yahoo holds second place in the mobile search race, with 18 percent of the market. Microsoft, at third, lords over a paltry five. (Percent.)

What's more, Google mobile searchers search more often — nine times per month on average. Yahoo mobile searchers query about 6.7 times per month.

Google is the default search engine on iPhone. In February it reported that iPhone users search Google 50 times more often than users on other mobile handsets.

Google is also the default engine on Opera's mobile browser. And it is currently closing a deal to become the default engine on Sprint mobile devices.

But while companies are happy to jump into bed with the search giant, user experience is not uniformly positive. 44 percent of Google users called their experiences "overly positive," versus 40 percent of Yahoo users.

(More findings available at MarketingCharts.)