Probably not surprising to readers of this site (ars):
Google managed to spank the rest of the mobile search world during the first quarter of 2008, according to data from Nielsen Mobile. The search giant managed to capture 61 percent of the mobile search market in the first four months of the year, with Yahoo! taking a very distant second at 18 percent. MSN sat at third place with a measly 5 percent.
The main reason: the iphone.