Diamond Age

Last night I started re-reading Neal Stephenson's book, Diamond Age. It's set in a not-so-distant future, post nanotechnology. Since I haven't heard much on this front in recent times I was wondering if people ever thought about it. Would you mind having little tiny man-made creatures whizzing around your bloodstream doing things? What if they were used for surveillance and tracking? Anyway, these are thoughts I've had this morning.