Worldwide marketshare for the iPhone OS platform has overtaken that of Symbian OS for the first time, according to the latest AdMob Mobile Metrics report (PDF Link). The report states that iPhone OS’ worldwide operating system marketshare increased from 33% to 40% between February and August, while that of Symbian OS fell from 43% to 34%. Worldwide marketshare for BlackBerry devices slipped from 10% to 8% over the same period, while the Android OS’ share jumped from 2% to 7%. According to the report, the iPhone OS now accounts for a “substantial” share of the market in all regions except Asia and Africa, and the iPhone is the top handset in the world for mobile usage, followed by the iPod touch. The same can be said in the North American, Western European, and Oceanian markets; the iPhone is also the top handset in Eastern Europe, followed by the Nokia 6300 and iPod touch in third place, while the iPod touch tops the Latin American market, followed by the iPhone. AdMob’s Mobile Metrics Report is based on ad requests from the company’s more than 9,000 mobile sites and 3,000 applications.