Ben, the maps are produced by a Mathematica program I wrote specifically for this purpose. It reads a GPS track (e.g. from a GPX file) and overlays the path on top of imagery downloaded from Google maps. Unfortunately, the Google maps downloading is quite unofficial and somewhat fragile, so I can't really distribute that part for other people to use. However, if you would like me to make a map for you I'd be glad to do it. Just email me a GPX (or some other) file from a GPS device (or even just a list of latitude,longitude values).