This release inlcudes an update to TinyMCE which fixes a number of issues since the release of TinyMCE 3.4.
A number of bugs relating to media elements (flash etc.) and script elements have also been fixed (users may have had trouble saving in some cases when inserting these elements) and some minor fixes have been applied to the Preview plugin.
A new List plugin has been added as part of the TinyMCE update which improves support for ordered and unorderd list elements, as well as an Autolink plugin which automatically creates links from urls in articles, a feature already present in Internet Explorer.