I have noticed that motion sensors on burglar alarms don’t detect small movements. Presumably they are also less effective at detecting small objects that move (otherwise they couldn’t be used if there were mice).
For an adult to move slowly enough to avoid detection by the typical cheap burglar alarms is quite difficult, and probably almost impossible to do reliably. For a small machine to move slowly enough that it’s combination of size and speed doesn’t get detected would be much easier.
So it should be possible to design a burglary robot that can open doors and crawl across the floor slowly enough that the alarms are not tripped. Such a robot could step over laser beams (which you always have in movies) much more easily than Catherine Zeta-Jones and then crawl up the wall to the motion sensor and disable it.
In a movie such a robot would probably be autonomous, but for constructing one in real-life 802.11 control would be the way to go.
If someone from Hollywood is reading my blog, please feel free to offer me an obscene amount of money for this idea. ;)