BTW, Nick - the answer you've read on the Internet is, unfortunately, correct. Neither the EOSinfo utility linked above, nor the Linux utility gphoto2 (which supports some cameras that EOSinfo doesn't) can read out the shutter count of a 20D.
Thanks Neuro, once again. You're like a guru.
It is unfortunate that it seems you're the only one that actually read what I wrote and answered accordingly.
(and thanks to you too dr croubie, but it seems gphoto doesn't work either... so I won't post you my camera )