In the above scenario, one logical document completes the whole transaction. The document is the center of the universe and not the applications that use it. Joe's Supervisor electronic signing applet may add encrypted billing information, but Joe may not see this. Only the Purchase applet on the backend will understand how to decode the billing information. It does not have to be manually entered reducing the possibility of errors.
Security is enhanced using public key encryption.
This entire workflow can be done using only the mouse. Agents could simplify the process even more saving your wrist from repeated motion disorder. Keyboard entry will seem as quaint as using punch cards for data entry. This above scenario is not a part of a big vision thing. We have all the building blocks to make it come true in the next two years.