On the off chance you haven’t heard, we shipped the first beta of the next release of the Windows Phone Developer Tools last week. The Windows Phone Developer Tools 7.1 Beta allows you to target both the next version of Windows Phone (Mango) as well as the current version (WP7). There’s also a “Go Live” licence so you can use the Beta release to develop and publish applications.
You can download the Windows Phone Developer Tools here. And the release notes are available here. It’s also possible to download an ISO image if you’re expecting to install on multiple machines (or multiple times).
You can find supporting MSDN documentation covering what’s new in this release along with a selection of code samples.
There’s also a good Windows Phone Developer Blog entry that summarises many of the new capabilities.