Review Board 1.6.4 is out the door!
This is primarily a bug fix release, but with a few added goodies.
Administrators trying to move Review Board to a different type of database (for example, SQLite to MySQL) can now use new database dumping and loading management commands. These will store the database in a database-agnostic format and load them back in. It's not a fast process, but should make life a lot easier in these situations.
Some changes were made to the webapi for compatibility with future RBTools releases. The 0.5.0 release will end up requiring at least Review Board 1.6.4.
Along with these, there's a new hosting service entry for Codebase HQ, issue tracking checkboxes in the Review dialog, and diff viewer improvements for Objective-C++ .mm files. And, of course, a large number of bug fixes.
Release notes are available.