Tom:
Sorry if this has been asked before, but I just upgraded to Fedora 7 and when I plug in my USB stick I get "Error org.freedesktop.Hal.PermissionDenied." The Details box says "Not inactive session".
I had the same 'problem'. I asked here (apparently no one knew). I finally figured it out for myself.
It happens only when I plug it in with X turned off (with Ctrl-Aalt-Fx). Just make sure that X is active (thus 'active session'), and it shouldn't give that error.