Google now has the world's largest provider of mobile-phone service, China Mobile, as a partner. But mobile search has far to go to be more than the niche service it is today.

China's a fine place to start, though. China Mobile, with about 300 million subscribers, including 4.6 million added in November, has the reach to spur mobile search. The deal means China Mobile will use its portal to give customers access to Google search, according to a deal announced this week.

Chinese mobile users are a lot more proficient with mobile search compared with U.S. users, says Yankee Group analyst XJ Wang. But even their searches are mostly limited to content like ring tones and screen wallpaper, rather than restaurants and shops that could most easily lead to ad revenue. Google also faces competition from companies such as the Chinese search engine Baidu, which has a deal in which Nokia installs an icon to reach Baidu's mobile search services.

In the U.S., mobile search is even more nascent. U.S. service providers haven't partnered with Google the way China Mobile has. There have been a few mobile-search deals in the U.S., says William Ho at Current Analysis. For example, Microsoft Live is working with Sprint, JumpTap with Alltel, and Verizon Wireless offers its own branded searching, using a Seattle company, Medio. Yahoo has a relationship with Cingular and Nokia.

Carriers know they will need to offer search for mobile Internet to be relevant. But today's experience, including the user interface on cell phones, falls short of what most people will accept. "But the ramp is developing, and it will certainly be much more common in two to three years time," says Gartner's Tole Hart.

Google must be hoping this is another emerging mobile technology that takes off in Asia, but eventually finds its way to the U.S.