[quote=TheDookieNut]
Actually data is used. Take Facebook for example:That now refreshs and updates in the background, as in when minimized not closed. On another note, I've used 15mb on this site so I don't think using 3G/4G is an issue for the site, as loveable as a mobile version would be, the site is usable at the moment. Perhaps for andriod users, trying a different internet browser
[/quote]

There's no dispute that actual data is used. 

However, my point is that apps which take advantage of Google Cloud Messaging (so, in other words, not Facebook) can get their notifications pushed along with Gmail and other Google app notifications. Because Google owns the front-end (Android) and back-end (GCM), they can do this more efficiently than an ad-hoc push server, like Facebook's, which saves the user data and battery power. Apple's iOS has a similar method as well.

This means that, with GCM, push notifications are virtually free if the user is also getting Gmail, Hangout, Calendar or other Google notifications anyway. The iOS version should work similarly, basically only establishing a data connection when there is content to push, not just regularly checking in and wasting data.