The release version of the Windows Phone SDK 7.1 is now available. This is the SDK used to create applications for Windows Phone 7.5 (Mango), and follow on from the early beta at MIX in April and several subsequent updates. The release version adds support for seven additional languages, puts the finishing touches to the tooling experience and fixes a small number of bugs.

As part of the release developers are recommended to carry out two actions:

1. Download and install the update SDK.
     
2. For application that have already been submitted to App Hib, log in and check you have cross-submitted your apps to the new Windows Phone 7.5 markets.
      

On the blog post detailing the SDK release Microsoft also share some interesting numbers on developer engagement:

• Hundreds of thousands of pre-release WPSDK downloads over the last few months
• 70,000+ unique developer devices have been successfully updated to ‘Mango’ over the course of the last three months
• 50,000+ visitors to the JumpStart videos, serving up over 450,000+ hours of video
• 20,000+ UserVoice votes submitted against 550 suggestions so far since the UserVoice forum launched with MIX
• 4200+ user posts in the ‘Mango Update’ App Hub forum, with 285,000+ post views
• 50+ cups of Tully’s Coffee consumed while processing Connect invites
• 8 devices came back to Redmond to receive intensive care

More information here.