Comment 13 for bug 249404

You don't need to run nm-applet as root...

I ran into this problem with a dist-upgrade performed today.

Simple way to get it back up and running is to kill any nm-applet currently running, then starting it back up...

pkill nm-applet
nm-applet

that's all I had to do to get it back up. Maybe the nm-applet crashed, but didn't release the dbus resources?