Announced today at WPC. Get it from: http://www.microsoft.com/downloads/details.aspx?FamilyID=c8496c2a-54d9-4b11-9491-a1bfaf32f2e3&displaylang=en
Check out this post on breaking changes from CTP to Beta: http://blogs.msdn.com/b/jaimer/archive/2010/06/28/migrating-apps-from-windows-phone-ctps-to-the-beta-build.aspx?wa=wsignin1.0
I'll post my feedback once I've installed it and tried it out.
Notice this under "System Requirements:"
This Beta of the Windows Phone Developer Tools is compatible with the final version of Visual Studio 2010
This has made my day :)