Through the deal, Yahoo expects to extend the mobile service it launched earlier this year to several million more potential users. Previously, it was available only to users of Nokia phones running the Symbian operating system.
"By bringing Yahoo Go for Mobile to to Windows devices, we're opening up the service to a whole new set of consumers," said a Yahoo spokesperson. In particular, Windows Mobile runs mainly on high-end devices favored by professionals. These include the Palm Treo, the T-Mobile MDA and the HP iPAQ, in addition to the Motorola Q and Pocket PC.
Windows Mobile comes with Microsoft Office, Internet Explorer, Outlook and select MSN features such as Hotmail and Messenger.
Yahoo Go for Mobile includes a variety of the Internet giant's online services including e-mail, search, and Yahoo Finance and other content. The service was started in January as part of a broader effort by Yahoo to extend its Internet franchise beyond the PC to mobile devices and TV.
Weston Henderek, a wireless services analyst with research firm Current Analysis, noted that Windows Media phones still represent only a fraction of the wireless market. And users have to be willing to download the Yahoo mobile software to those devices.
"For Yahoo to be successful with this application they will need to get handset manufacturers and carriers to have it embedded on the device before the customer makes a purchase," he wrote in an e-mail.
Yahoo did sign deals earlier this year with Motorola and BlackBerry-maker Research in Motion to have Yahoo Go for Mobile pre-loaded in certain of the companies' devices. But no Motorola or RIM devices with Yahoo Go for Mobile have shipped yet.
The mobile partnership beween Yahoo and Microsoft may also add to speculation that the tech titans are forging closer ties to fend off Google. In a June report, Merrill Lynch analysts argued that Google's continued gains in search market traffic, combined with its recent focus on software, increases the likelihood that Microsoft will buy Yahoo or eBay.