Here's some info my dad sent me he's actually involved in the project on the Transit Wireless side

http://www.link.nyc/

https://drive.google.com/file/d/0B2ziLFANXR9deEJPMmZQcUNUT0l...

I really hope it is just advertising on a captive portal, and not content injection

"Advertisers can reach subway riders in many ways such as sponsorship of Free Wi-Fi, landing page banner advertisements, video advertisements and application downloads"