Opera is the world's number one mobile browser, overtaking the iPhones Safari browser in May according to data from StatCounter Global Stats. In May, Opera took 24.6% of the worldwide market, compared to 22.3% for iPhone. Nokia retains third place with 17.9%. BlackBerry is in fourth place, with 6.9% of the global market. If the iPod Touch is included, however, Apple browsers still lead, with the iPod Touch alone taking 14.9% of the market in May.
StatCounter, which provides free website traffic analysis, records in excess of 10 billion pageloads per month. In March, it launched StatCounter Global Stats, a free online service which captures market share of search engines, browsers and operating systems, including mobile.
You can see regional and country browser analysis here. 
