Microsoft (NASDAQ: MSFT) is paying iPhone game developers to port their titles to its new Windows Phone 7 in an attempt to increase the number of available applications at launch for its new mobile platform, according to a new report from Pocket Gamer.

The report suggested that Microsoft is contacting successful iPhone game developers and offering substantial sums of money up-front to produce versions of their software to Windows 7.

Microsoft has not commented directly on Pocket Gamer’s claims but said that it does offer “limited” financial support  ”most commonly in the form of an advance on revenue” among other resources.

Last year, Microsoft announced a clear set of rules for publishing apps on its mobile marketplace in an attempt to provide differentiation for its platform to Apple’s, which has previously received criticism from developers for arbitrarily rejecting applications and allowing applications to sit in a holding pattern for an extended period of time to await approval.

The move hasn’t been enough for Microsoft to attract developers away from Apple, despite the 30 million users that run versions of Windows Mobile 6. Microsoft had also offered technical advice to developers wishing to convert iPhone applications to Windows Mobile 6.5.

Microsoft will likely need to do more to woo over developers than provide technical assistance or up-front cash offerings to win over the hearts and minds of developers. Microsoft’s platform (Silverlight and XNA) is much different than Apple’s Objective-C Cocoa and will take a significant investment of resources to support an additional platform.

Some might be willing to make the upfront investment in time and effort, but many feel that Windows 7 is still too speculative to invest in. The unreleased operating system has no market-share and Microsoft’s commitment to the platform isn’t known. Apps cannot be ported back to Windows Mobile 6.5, 6.0 and 6.1 devices, limiting sales to a future, unknown market.