Back at Mobile World Congress in February, Steve Ballmer announced Windows Mobile 6.5 and a set of complementary Services – MyPhone and Windows Marketplace for Mobile.
The Marketplace is now open for Developer registration – this enables you to register with the Marketplace as a developer, and start developing applications to be distributed via Marketplace to Windows Mobile users worldwide.
So the steps you need to take are:
1. Register at http://developer.windowsmobile.com/marketplace.aspx. (you’ll need USD$99 and a LiveID)
2. Get the information & tools to develop for Windows Mobile from http://msdn.microsoft.com/windowsmobile
3. Get developing your innovative applications