In this update there have been a lot of new features added and a ton of bug fixes. If you would like to check out the full list of new features and changes you can do so here.
Packages are also available in the same topic as the release was made - here
This release is quite significant as that it is the turning point to the new release model. After 3.0.6 is released work will soon begin on 3.1, which will be the same as the 3.0 releases except with additional features. I think I can safely say we are all really happy for the new development release cycles as it will provide stepping stones with new features over the initial release with a relatively short development time frame. No more waiting 5 years for a nearly completely new version to get new features.
Kudos to all of those involved in the phpBB project.
