It's striding toward us from the kitchen, smoothly and silently. As I set down my overnight bag and turn to question my friend Jack, it ambles gracefully into the foyer. I can sense Jack watching me out of the corner of his eye, looking for a reaction as his newest purchase stops and stands beside us on two thin mechanical legs and clasps two four-fingered hands behind its back. It's smaller than the average person, lithe, entirely unthreateningI could take it in a fight. The face isn't human, but it's not the face of an appliance either.