This is another nice CKEditor release, introducing several exclusive features into the editor, like BiDi support, the ability to resize table columns with a mouse click, enhancements to the TAB key navigation on tables, support for read-only regions, the good and old autogrow plugin, among others.
Although we're confident on the stability of this version, we've releasing it as Beta, to give our community a chance to test and check the new features. The final release should be out in two weeks.