In Marc-Andre's own words:
This Lego Wall-E is entirely controlled via the NXT using NXT-G program. The chains are driven by 2 large PF motors connected to IR receiver. The arms go up and down individually using the 2 other smaller PF motors on another IR receiver. Both the receivers get their command thru the HiTechnic IR LINK Sensor via the NXT.The NXT servo motor are used for opening/closing of the hands and 2 more are used to move the head right/left and up/down. I have used 2 gearbox (with wormgears for the arms) and one for the head. Most of the yellow lego is from the Bulldozer kit from which i also took the Chains and PowerFunctions
More pictures can be found here.