The highest priority story in the EntLib5 backlog is ARC01: Architectural refactoring, which includes the use of a dependency injection container for wiring your EntLib objects instead of the one-off ObjectBuilder factories and DI container independence (to allow other containers such Spring.NET, Castle/Windsor, StructureMap, Ninject etc. to be used instead of Unity if you prefer so). This work is now complete. For details of this architectural update, please see an easy-to-read summary by Bob Brumfield. We also touch on this in the channel9 video.
As usual, the updated bits are available for preview on Codeplex - http://entlib.codeplex.com/SourceControl/ListDownloadableCommits.aspx