Not much I'm afraid. Workflows and other collaboration features will be addressed after 3.5
We implemented some pseudo workflow stuff, sometimes (but mostly not) coupled to the notification system. Some boolean flags in the classes are used to hide/show (read "publish") objects.
Collaboration features are really the weakest part in eZ publish, at least when you need something more than a simple workflow.
Just some information: I've just made some extensions for a customer which supports multi level approval. I also made it possible to edit the object during the approval workflow.
This code is not (yet) ready for trunk, but atleast the editing during a workflow event should be in trunk soonish. There are some generalizations that needs to be done before I can commit it.
So, there are some improvements beeing done in this area.
These new features will not be added to the 3.4 branch. No new features will be added there. So it might be added to the 3.5 release, but I can't promise that since it's not part of the features we will make for 3.5.
I hope we will have time to clean this up for 3.5, but I can't promise it.
I found this topic by searching a solution to add a validation workflow for only one class, because I'm on a 3.8.6 version, and the validation workflow can just be defined for a section, and in my section I want to validate articles but not comments.