Some information on Luxo Jr's history...
The idea for Luxo Jr was originally much much smaller scale. He was going to sit on the Pixar sign at the entrance to Pixar Place in place of the "I". Occaisionally he would move around a bit, tilting his head around and such. At some point in time, someone realized (don't know who) that this would be very hard to see so work was shifted towards what you see to day. The budget of course exploded and the time line kept getting pushed back more and more. From what I was originally told, the idea was to have him up and running sometime late last summer, which of course did not happen. Luxo Jr is also the first completely electric animatronic (at least from the information I had 1+ year ago, the design could have changed) Disney has done which explains the buget and time line over runs. Other AAs movement is produced by hydraulic actuators with some pretty fancy electronics controlling the flow of hydraulic fluid.
I think that just about summarizes what I know about him. If I remember anything else I'll post it here.