Hi Alejandro,
The roadmap of jBPM 4 on the JIRA almost out of date. Sine Joram left jboss, the issue of BPMN2 should be delayed to version 4.x. And there are still a lot of unfixed bugs, some of them are serious blocking developer to use it in the production envrionment. Fixing bugs and releasing a new version in the near future is the best solution to stablize the community.
By the way, the AttachmentTest is failure in the current trunk. I had post it in the development forum. If you have time, please have a look at this.
http://community.jboss.org/thread/151017
I would like to do anything on keeping maintaining jBPM 4. If you are looking for contributors, please let me know. Thank you very much.