Here's a scene from Minority Report with an imagined advertising landscape after automatic recognition becomes common. The assumption was that retinal scans would be used instead of facial recognition, but the imagined scenario is apt.
It's even more apropos when we consider how many people in the future may be wearing Google Glass-like augmented reality devices. In Minority Report, you might see someone else's advertisements, but if they are projected directly on your viewscreen (or retina, etc) then advertising and propaganda gets even more creepy, as it's more private.
A plausible version of such a dystopian vision is one where your new glasses get infected with malware that spams you with advertisements, which I believe I read about in a novel by Gibson. A more frightening one would be one in which what you see is based on propaganda.
Speaking of retinal scanners, I've heard of a high-res scanning camera that can acquire a retina (or maybe it was iris) every ~1.2s IIRC, from people just wandering around. I'd like one in my home, but not in public.
