Pete, can I suggest putting a sticky with a link to this file or at least a link to the page (Page 1 of Panel Design) telling people which file to look for?
It seems like a good tutorial, especially where XML is concerned. I'm finding out the hard way there's a severe lack of info out there when it comes to creating panels and from the questions I've seen, I'm not the only one. It couldn't hurt to point people in the right direction...
Kevin