NOTE: The 'b' in '4.0b' is does not mean it's a beta release. It's a stable release, just as the previous stable version, 4.0a, was not an alpha release.
While I work on a more complete set of release notes, you can take a look at the following to get an idea of what was updated in this release:
Guide template name change are now reflected immediately in the Guides menu
Director of Engineering for Enterprise and Operations