Microsoft is allowing Windows Phone developers to update their retail Windows Phone to Windows Phone Mango pre-release to test applications.
"Coinciding with the update Windows Phone 7 Developer Tools release comes the new beta Windows Phone SDK, a new program via Microsoft Connect will allow you to upgrade your Windows Phone retail device to a pre-release build of Mango."
You will now be able to run and test your existing and new Mango applications on live Windows Phone devices running a pre-release OS build of Mango. You can also test functionalities that couldn't be tested using the Windows Phone emulator alone, including performance profiling, full use of device sensors, and running and debugging apps that make use of the background agents.
Invitations were sent out from Microsoft Connect to currently registered Windows Phone Marketplace developers.
Developers are invited by email to their registered accounts.
"Please, update your phone to Mango and test your apps today to better understand what your customers will experience when they upgrade their Windows Phone devices in a few months. If you run into problems that are OS or API related, please file a bug within the Connect program, and we will do our best to help address the problem," said Microsoft's Windows Developers team.