To get this example running, you need to do a couple of things.

First of all, you have to install the .server file into
<prefix>/lib/bonobo/servers where the panel will find it.  Afterwards, you
possibly have to kill the gnome-panel process so it recognizes the new applet
(the panel will be restarted automatically by the session).

Then you have two options: A) the normal procedure is to let the panel spawn
the process for you, but B) it's also possible to launch the applet manually
and then have the panel attach to it.

A) For the normal procedure, you have to specify the full path to the
   executable Perl program in the .server file.  In case you have the relevant
   Perl modoules installed in a custom location, you will also have to tell
   perl where to find them (see the comment in perl-applet).  Now, adding the
   applet via the panel will start the program.

B) For the manual variant, just start the program from a terminal; it will
   block if everything's alright.  Then add the applet via the panel normally.
   The panel will attach to and use the running instance.  This second approach
   has the advantage that you can actually see debug output.