Apple’s iPhone held onto a 13.7% share of global smartphone unit sales in the second quarter, outpacing Microsoft’s Windows Mobile, which now claims just 9% of the market, according to Canalys.

“Apple has revolutionized the smart phone sector, leapfrogging more experienced rivals,” Canalys senior analyst Pete Cunningham said in the company’s report. Sales in the second quarter did not include much of the surge in new sales spurred by the release of the iPhone 3GS.

In the North American market, the iPhone grabbed a 23% share of smartphones sold, despite being tied to a single carrier in the US. Apple’s US debut occurred months before sales were expanded to other countries, and international sales of iPhone really began a year later with the launch of the iPhone 3G. RIM held a commanding 52% share of US smartphones.

In Europe, the Middle East and Africa, Nokia maintained a 64% share while Apple took second place with 13.6%, followed by third place RIM with 10.3%. Those numbers indicate Apple has been much better at competing internationally against Nokia than RIM has, despite its having been in the smartphone business for nearly a decade compared to Apple’s barely two year old iPhone assault.

Worldwide, Nokia still leads smartphone sales with 44.3% of the market, but that represents a significant slide over the last few years. As recently as 2006, Nokia’s Symbian platform accounted for over 72% of smartphones sold; now it represents just 50.3%.