Even though Nokia didn’t start selling Windows Phone smartphones until November of 2011, it already ranks as the leading seller of Microsoft’s mobile operating system, Forbes reports.

Microsoft and Nokia are hoping that the emerging partnership will propel both companies into the highly competitive mobile industry.

Nokia has been noticeably absent in the American market in recent years and is putting all its eggs in one basket with its new line of Windows Phone smartphones, including the yet-to-be-released Lumia 900.

“Global smartphone shipments using the Microsoft operating system grew 36% sequentially, to reach 2.7 million units in Q4 2011,” said Alex Spektor, of Strategy Analytics. “Microsoft smartphone shipments remain tiny, but they are showing tentative signs of growth. Nokia overtook HTC and others to become the world’s largest Microsoft smartphone vendor, with 33% market share. Nokia’s global Microsoft smartphone shipments hit 0.9 million units, as distribution of its Lumia family expanded across numerous countries and operators.”

Eric Zeman of Information Week notes that Microsoft and Nokia still have a long way to go before they can declare any sort of victory.

“Microsoft and its handset partners sold only 2.7 million Windows Phone devices during the fourth quarter,” he writes. “Keep in mind, that’s a global number. In that same time period, Apple sold 37 million iPhones and Samsung sold 35.6 million (mostly Android, though Bada and WP7 is mixed in that number).”

But Windows Phone has only the tiniest toehold on the U.S. mobile market.

Zeman continues: “Looking only at U.S. figures, Android has 46.3% of the market, while iOS has about 30%. RIM’s BlackBerry platform is third, with about 15%. The remaining 10% is owned by Windows Mobile, PalmOS, webOS, and Windows Phone. Windows Phone has about a 1.5% share of the U.S. market. Windows Phone’s percentages in other markets aren’t much better.”