To try RC2:
Here is the release notes for Movable Type 5.1 RC2. Please note that minor cases are not listed here, 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.
We look forward to hearing from you !