Sharing with Sugar
Though earlier Live CDs may not application share, I just tried out the most up to date image
XO-LiveCD_080321.iso from http://dev.laptop.org/pub/livebackupcd/build-695/
Download the ISO image and burn it to CD, then put it in a PC and boot. It boots ok if you have >256M RAM
Though the Live CD doesn't seem to support WiFi, I was able to use ethernet on the PC and WiFi on my OLPC and application share. That means that the educational advantages of Sugar's application sharing can be evaluated without needing multiple OLPCs.