Hi Bryan
Suggest you post a new discussion in the BPM forum - this one is over two years old.
Also you need to be careful with your terminology. PO is generally used for Process Orchestration - the Java based PI+BPM+BRM combination that supersedes PI (Process Integration).
Process Observer is part of ABAP - think of it as a module - I've never seen it referred to as PO.
The information exposed by Process Observer can be used by calling applications- in fact that is core to the Operation Process Intelligence (powered by SAP HANA) solution - which derives underlying process information from ABAP via Process Observer, BPM, and other sources.
Rgds,
Jocelyn