Thanks for the feedback Maciej and Tihomir,
Maciej, I agree that your idea can work but I would prefer to not have to create any kind of overhead for the runtime, not that it is a big issue, but I really see this as a design time problem and I also want to provide as much as built-in features as possible for the person who will design processes. I also want to avoid process to follow certain kind of structure, I really see it as a service that my API could provide, but to accomplish it I need these variables to be in every process. It is my vision, for this reason I brought it to table to discuss with the experts like you guys :)
I really like this process template idea Tihomir, I can see a lot of benefits, like guidance for new process modelers. Just thinking that it might be a different feature, the reason why is that even if you import a template, the modeler still free to do pretty much anything he wants on the model. I think these "pre-defined" variables would need to be locked somehow. I just imagining the case about the user variable for storing who started the process. This will probably be the only link I would have to trace all process started for a certain person, so this variable would need to exist in all process instances. Unless a process variable is not the right place for doing it, but in the other hand you also have the possibility to reuse within the process, like assigning tasks for the same user that started the process.
For sue, I can definetely help with it ;)
BTW, nice job on the jBPM Designer, great stuff B-)