Hello,
We are actually using jbpm5 within our application development framework to orchestrate, through bpmn 2.0 models and jbpm5, our software systems. The systems are implemented, executed and controlled based on the designed models. So in a sense the architecture of these systems is defined within those models, as well as any integration points with other systems/services i.e. calling published web services through jbpm5 work items. Hence the cocepts of MDA/MDD are pretty much met, however I'm not sure to what extend it is aligned to the exact concepts of OMG on these matters.