Android overtook Symbian in the fourth quarter of 2010 to become the world’s largest mobile operating system in terms of shipments, according to data released today by Canalys. That may not be much of a surprise to those who follow the industry, but there’s no denying that Google’s OS has gained tremendous momentum over the last couple of years. But as my colleague Ryan Kim points out, mobile is still a wide-open space: Apple will get a boost from a Verizon iPhone, Microsoft will continue to aggressively push its Windows Phone 7, and Research In Motion may have a winner with its QNX platform. There are plenty of other factors at play, too, including the nascent tablet space and Symbian’s still-massive footprint. This game is far from over.