Beta Mango tools in ISO format

The new Windows Phone Developer Tools 7.1 Beta , Mango can be used to develop Applications for both 7.0 and 7.1 version of Windows Phone OS releases.

You can download this release in .iso format for offline installation.  (717 MB)

Else if you want web installer and for more details please check here.

The Windows Phone Developer Tools includes the following-

Microsoft Windows Phone Developer Tools 7.1 (Beta)

Windows Phone Emulator (Beta)

Silverlight 4 SDK and DRT

Microsoft XNA Game Studio 4.0 Referesh Windows Phone Extensions

Microsoft Expression Blend SDK Preview for Windows Phone 7.1

WCF Data Services Client for Window Phone 7.1