The announcement was made in a blog post today by Todd Brix, senior director for mobile platform services and product management at Microsoft. He said the Marketplace will initially open for developer submissions on July 27, and then will be available to consumers this fall along with the launch of the first Windows Mobile 6.5. It will initially be available in 29 countries. The marketplace will then open up to older operating system versions by the end of this year.

Brix wrote: “We’re already working with a wide range of leading developers for both business and consumer applications and will soon be able to make available a new wave of applications that will be ready for download when Windows Marketplace launches with Windows Mobile 6.5 in the fall. To make things a little more interesting, later this month we’ll also be announcing the details of a developer contest that will kick off at launch.”

Microsoft also announced the Windows Marketplace Business Center, which will be a category within the app storefront that will feature business applications. This is smart since Windows Mobile has traditionally been adopted by a lot of business users. Companies that expect to particpate include: Avanade UK, Formotus, Ilium Software, Pyxis Mobile and WebIS.