http://www.newscientist.com/article.ns?id=dn7023
I just found this very interesting how they use gravity and springs on top of motors to match more realisitic human walking conditions. Also the robot is able to adapt to different walking conditions.
P.S. I did a search and couldnt find anything of the sort if there is another thread on this already alert me and I will be able to delete this within 24 hours