[dnastase]

That sort of is my point HarryT. They manage to keep the wifi on from our perspective (see below), use it and still not waste battery.
(I still believe that wifi radio is turned off when OS deems it appropiate. You just don't see it. It's not like wifi setting is turned off but the radio. It's true that push notifications work, but you don't know the latency of that or how many retries the server does until it gives up. Obviously for usage generating from inside the device, the OS will know to turn the radio on).