10K Google Wi-Fi kiosks are collecting millions of faces and MAC addresses
massprivatei.blogspot.com
massprivatei.blogspot.com
To your point about reasonable expectation of privacy. On the surface, yes, you do not have a reasonable expectation of privacy in public, however, I do not like the idea of having my picture tied to identifying information like a mac address. It starts to provide a fuller picture of a person and would allow more data in which to build up a profile.
At the end of the day I'd like to choose how and when my personal information is exposed (to the extent that I'm realistically able to control it)
INFORMATION COLLECTED BY OUR SENSORS AND CAMERAS ... We will not use facial recognition technology for any reason, and we will not use our cameras to track your movement through the city.
http://www1.nyc.gov/assets/doitt/downloads/pdf/Proposed-PCS-...