The deal is ending at the end of this month, but it has now been expanded and is available at over 4,000 locations around the US, including 15 major airports like New York’s JFK Airport, Chicago O’Hare, and Seattle-Tacoma airport. Unfortunately, the hotspots aren't open to just anyone. You have to have either a Windows or Mac PC or an Android device, iOS, Windows Phone, and BlackBerry are not supported.
The deal is actually a partnership with Boingo and Google Play, not just plain old Google, and supposedly there will be access to "free content" as part of the deal. It isn't clear though if that means free Google Play content or not, but given Google's love of free stuff, it wouldn't surprise us.
source: The Next Web