I tried all of the above test:
1. gnome-power-manager --no-daemon --verbose does not produce any output. I tried clicking the inhibit applet and changing panel brightness and there is no output at all.
2. grepping /var/log/messages for gnome-power-manager produces no results. I also tried grepping /var/log/syslog which I believe should be the more detailed log, and there isn't anything there either.
3. stopping hald and running it from the command line produces a lot of output for everything in the system, but after it settles down I tried to play with the inhibit applet and I got no output. Playing with the panel brightness got some reports from hald about "IBM hotkey" and "Video LCD0"
Given that, it seems to me that inhibit applet 2.27.1 simply does not respond to mouse clicks for some reason.