jbrodkin writes: Windows is on the verge of dropping below 90% market share, with smartphones and tablets posing an increasingly serious threat to Microsoft's dominance of the operating system market. Data from Net Applications — which lumps mobile and desktop operating systems into one statistic — show that Windows market share dropped from 93.74% in February 2009 to 90.29% in December 2010. "The operating system usage market share trend line points to Windows' overall usage falling below 90% sometime during 2011," says Vince Vizzaccaro, executive vice president of marketing and strategic alliances for Net Applications. "It could be as early as next month." Although Windows-based PC shipments are growing, the data points to the fact that the rest of the OS market, driven by mobile devices, is getting bigger and Microsoft isn't capitalizing on the growth. More and more users are accessing the Internet on devices that don't run Windows. Another analyst predicts that "By 2013, greater than 67% of browsers accessing the Internet will be on non-PC devices. Internet Explorer will ultimately become a minor player in the browser market."