Just before the launch of the new iPhone, Google Play has inked a deal with Boingo to give free WiFi access to virtually all devices – just not the mobile ones from Apple. The over 4,000 sponsored Wi-Fi locations include 15 airports as well as Boingo-enabled Manhattan subway stations, and thousands of hotels, shopping malls and cafés.
Google has sponsored free WiFi in airports and other locations so this isn't necessarily a new strategy. To date however, I am not aware of them excluding other devices.
The free Boingo Wi-Fi lasts through the end of September. And in case you are interested in the official reason why iOS devices are excluded, here it is: “Google Play is a content platform designed for Android devices, and this Wi-Fi sponsorship is focused on reaching Android tablet and phone users as well as Windows and Macintosh laptop users.”