The Movable Type 5.1 RC3 is available to download now.
To try RC3:
Here is the release notes for Movable Type 5.1 RC3. There are couple of bugs (such as 106201) which have been reported recently, and we may roll another RC release shortly.
Please see FogBugz for all cases.
For more details:
Your feedback is important to get Movable Type 5.1 ready for the final release. Without your feedback, it is almost impossible for developers to test the software in all of the various conditions that might occur. So please don't hesitate to create a new case.