In all examples involving “servers” there is a try ... finally block:

try:
    # some code
finally:
    # Unregister the DBus service and objects.
    SESSION_BUS.disconnect()

I would suggest to natively support the PEP 343 with statement, in order to allow refactoring the above code as

with SESSION_BUS:
    # some code

The implementation using with-statement context managers should be straightforward.