With the latest update to http://developer.windowsmobile.com, Microsoft now allow developers to register to participate in Windows Marketplace for Mobile. According to Microsoft's Windows Mobile Team blog, this marks another milestone in providing Windows Mobile Developers a clear path to develop, test, certify and distribute their Windows Mobile applications via the Windows Marketplace for Mobile. Throughout the registration process, links to key documentation for distributing apps through Windows Marketplace for Mobile are provided.
While Windows Marketplace for Mobile isn't yet operating, it's expected it will be launched together with the release of Windows Mobile 6.5.
