I did a little investigation, and UpdateStatus appears to be a signal (not a method), so it's probably just notification about the change in status of the GPS receiver and/or GPSD (on or off).

I've been trying to incorporate the new libgpsmgr/libgpsbt framework into Maemo Mapper, and while the libgpsbt framework uses DBUS to search for a bluetooth GPS receiver, the libgpsmgr framework that actually controls GPSD itself doesn't appear to use DBUS at all. Looking at the code in gregale/bora, I think libgpsmgr uses lock files to track GPS clients. There are new versions of libgpsmgr and libgpsbt, but Nokia appears to have closed-source them (grr!), so I can't see how they work. Perhaps the new libgpsmgr controls access to the internal GPS receiver.