You might want to add rur-ple (http://code.google.com/p/rur-ple); it is similar to Guido van Robot (and was inspired by it). However, 1) it uses Python (instead of a more limited, Python-like inspired language); 2) it has more lessons and exercises than Guido van Robot; 3) it provides an embedded programming environment to go beyond the robot's world.
A second addition to consider is GvR online (http://gvr-online.appspot.com/ui/index.html), an online version of Guido van Robot.