Review Board 1.6.2 is out. It's a bug fix release that takes care of several issues people have hit. In particular, it should have a proper Apache WSGI configuration for subdirectory installs out of the box, some SCM integration fixes, browser compatibility improvements, and various other things.
We also have a couple bits of new API for those who want to automate review group creation, or archive deprecated repositories.Check out the release notes for the full list.