Julius Schwarzweller wrote a blog post with a collection of links to CR3 for IBM Connections 5.0 this week. A official update document with new features is missing.
I installed it today (without CCM) and the first new feature i found is “sharing folders” with Communities:
As shown in the screenshot only public folders can be added to community files widget.
From files application you can still share a folder with people, groups and communities (but then the folder will be public available too):
