When Motorola (NYSE:MOT) announced late last month that it was selling its 19% stake in operating software conglomerate Symbian to fellow investors Nokia (NYSE:NOK) and Psion, speculation ramped up that it would join with Microsoft (NASDAQ:MSFT) to introduce new "smartphones."

After all, the world's largest software company wanted entry into the growing cellular phone software market, and the world's second-largest cell phone maker wanted additional means to differentiate itself from industry-leader Nokia. Sounds like a match, right?

Today, the parties made it official, with the marriage resulting in the MPx200 smartphone. The Motorola-branded, Windows-enhanced phone will be released and distributed in the U.S. this fall by AT&T Wireless (NYSE:AWE), and in Europe through the French wireless firm Orange.

Hoping to capitalize on Microsoft's desktop dominance, the new phones will come loaded with versions of Windows Outlook, Internet Explorer, and Media Player. They'll also have a memory card with expandable memory up to 1 GB.

Busy professionals will be able to quickly and easily sync up their cell phones with their computers to handle contacts, emails, or appointments. They'll also be able to download video clips or music, should they want more entertainment and less work stuff available on their handsets.

For Microsoft, the alliance marks an important move into a growing business segment. It's been wanting into the cell phone applications market for years, but largely shut out by Nokia and others.

It's a positive development for Motorola, too, though the company isn't going "all Windows all the time." It will keep making handsets with other operating systems, as well.

LouAnn Lofton owns shares of Microsoft.