Screenshot by Lance Whitney/CNET

Microsoft is sponsoring some free Wi-Fi sites in New York and San Francisco to drum up interest in Windows 8.

Six different Manhattan subway stops will feature free Wi-Fi starting immediately, and another 200-plus hotzones across the city will light up November 1. The subway locations are supported by Transit Wireless, which provides Wi-Fi service for travelers riding the rails underground.

Residents of San Francisco can surf at Microsoft's expense at hotzones in such locations as Union Square, Fisherman's Wharf, UN Plaza, the Financial District, and Nob Hill. The hotzones in New York City and San Francisco all come courtesy of Boingo Wireless.

The free service in both cities will be available until the end of the year.

With Windows 8 officially launching October 25, Microsoft wants to convince both developers and consumers to dive into the new OS.

The free Wi-Fi is part of a Windows 8 promotion designed to highlight the Windows Store for app developers. Microsoft also wants consumers to get accustomed to the Windows Store by browsing apps and trying out staff recommendations.

"At Microsoft, we know that amazing apps are being built in New York and San Francisco, and we want to give talented developers the chance to launch their businesses through the Windows Store," John Richards, a senior director at Microsoft, said in a statement. "We hope our Boingo Wi-Fi sponsorship will introduce the Windows 8 opportunity to app builders in NYC and San Francisco, while providing folks with Wi-Fi connectivity on-the-go."

Microsoft has lofty goals for the Windows Store.

A little more than 3,000 Windows 8-style apps now inhabit the store's virtual shelves. A company sales VP recently said that Microsoft aims to offer 100,000 Windows apps within 90 days after Windows 8 launches, meaning toward the end of January.

Driving that level of developer interest and activity will certainly pose a challenge. As ZDNet's Mary Jo Foley aptly put it, "unless there are going to be tens of thousands Flashlight apps introduced between now and January, or unless someone's doing some funny figuring, I am really hard pressed to see the Windows Store revving up this quickly."

Microsoft also needs to make sure that the built-in Windows 8 apps don't disappoint. Some of the apps are nicely designed, while others still seem half baked. Toward that end, Microsoft recently started beefing up some of its own apps, including Mail, Messaging, Maps, Photos, and SkyDrive.

But third-party developers will need more incentive beyond just free Wi-Fi if Microsoft expects to ramp up the Windows Store with another 97,000 apps in just three months.