All that the robot's circuit board contains is a voltage regulator, a basic stamp and a bread board. You should have no problem replacing the basic stamp for ANY microcontroller.
All you have to do is provide substitutes for the 16 I/O pins of the original basic stamp. An 8052 usually has P1 and P3 free, so there you go.
As far as programming goes: you'll have to start from scratch, but you could use the Basic programs as a guideline.
PS. I think Steve's hacked Furby was sexier, but you can't have it all.