Yesterday signified the end of non Mango devices being able to access Apps from the Windows Phone Marketplace. Microsoft officially announced that they have started requiring Windows Phone 7.5 on phones to download, buy, update, or review apps in Marketplace.
The Mango update to Windows Phone came out last September and brought a slew of new features such as Voice Control, improved social networking integration, multi-tasking and support for hardware improvements like front facing cameras.
Most phones are already running Windows Phone 7.5, which was released last fall, and so most of you won’t notice anything different about how the Marketplace works. However, if your phone has an earlier version of our software installed, you’ll soon start seeing an error message when you try to download a new app, or update one you already own. (I say “soon" because it will take a day or two for the changes we made today to take effect.)
If you run into the error, make sure you update your device to Mango – instructions on how to do this are available here.