Mark Tilden, the Nasa guru that designed Robosapien, has a very interesting and contrarian take on Asimov's three laws of robotics-
Interviewer: Let's talk nuts and bolts a little. What are the rules that drive these things? It's not Isaac Asminov's robot rules, right?
Tilden: No. Asmimov's rules were essentially, protect humans, obey humans, then look after yourself. During the 1980s I built a variety of robots like that, and I wound up with robots that were so scared about doing anything that could possibly displease human beings, that they just sat in the middle of the floor and vibrated. My cat had a field day with that.
Our rules are basic rules of survival: feed thy ass, move thy ass, and look for better real estate.