[ctdonath]

Per the comments noting that this (police-mounted face recognition) isn't a thing:

I'm amazed that pervasive face recognition isn't a thing. I figured it would be the killer app for Google Glass, popping up notes about everyone you see. Apple & Facebook could leverage it from the face tagging in Photos & FB. Police could be well-served by a vest-mounted lightweight system giving likely identifications of encountered suspects (or anyone) from mugshots et al. Thing is, all the technology is there waiting for use; it's a killer app just waiting for society to put up with it (just like privacy invasions that were intolerable back when and are normal today).

(I'm not necessarily advocating it, just figuring it's inevitable and ready to explode onto the scene.)

[Eridrus]

It exists in Russia under the name FindFace.