Comment 10 for bug 328575

Spawning a new bus when you get a security denial is not the right way to go.
Having a UID embedded sounds like the sane way to do this. If it isn't the
same UID treat it as if it is unset. I don't know if this breaks the spec
though. The check would be done in the unix socket transport layer and the
socket name editing would be in dbus-launch or somewhere in the bus/ directory.
 We have the guid= we could also have a sessionuid= part. Patches welcome (I
would look at the GUID code to get an idea of how to write this).

BTW while D-Bus is not tied to X dbus-launch is and will store the address in X
if an X connection is present when autolaunching a bus.

Also per user buses have been discussed at length and been rejected because of lifecycle issues. Please read the archives on the mailing list. If GConf needs to be per user it has to do that itself.