"We feel comfortable that using our LiveID system to help connect products to five devices is a great balance of the needs of both developers and end users," Bouie wrote in a follow-up e-mail. "We see this as a permanent feature, and we've gotten great positive feedback from the vast majority of developers we've talked with about this."

There are more than 20,000 apps available for Windows Mobile phones today on independent sites such as Handango.com. But are available for the iPhone after less than two years.

To get on the good side of developers, Microsoft is trying to position the marketplace as a and to Apple's App Store.

Microsoft earlier this month governing what apps it will allow.

Also, developers accepted for Microsoft's marketplace will be allowed to sell the same wares via other stores, Bouie said.