The team is starting to roll on CiviCRM v3.1. One of the sponsored items is the ability to allow one custom group to be used with multiple relationship types. I'll use relationship types as my example here. This feature will also work with other objects that can be extended: specifically In v3.0 and prior a custom group can only be used for one specific relationship type.
Blogs
In the course of the recent NYC Developer camp, I had the opportunity to discuss the state of CiviCRM's templating system with members of the core team . In the course of our work with CiviCRM we have done extensive theming and have discovered a number of opportunities for improvement over the current system.
A while back I wrote a forum post on how CiviGrant could be usefully extended to fulfill a wider function.
We've recently upgraded a copy of a 100,000+ contact install running 2.2.8 to 3.0 b3 for testing purposes. Functionality is fine and things look absolutely great in the new interface.
The upgrade was painless and quite quick. There was a foreign key drop constraint in the installer that needs tweaking, but the core team is on it and apart from that it took only about 20 minutes start to finish to upgrade the fairly good sized database.