Bingo. Killer app: face recognition. Add license plate recognition to that (per another current threagood money for a system that would, unintrusively, pop up an info bubble over everyone's head (name, summary of interactions, relationships, last social media posts, etc). Considering the data mining potential, I'd expect Google et al to provide the hardware & services for free or darned near it.

Add license plate recognition to that (per another current thread). Cars correlate real close with their owners.