It's based on usage. For example, if I use an HN reader a lot, that will get frequent updates in the background. But the RSS reader I haven't opened in a week will get less/no background updates since the OS knows I'm not using it too much.
It will not. First, it doesn't do this by default. Second, it does it based on your patterns, and even then it will pool connectivity to that apps aren't just firing off requests whenever they see fit (in other words, keeping the radio spun down as much as possible). Lastly, you can disable it. Battery saved.
I can imagine scenarios where it might increase battery life - prefetching means that you won't be staring at the battery hungry screen while waiting on data to load, for example.
I'm sure data-sippers and battery-hawks can configure settings it so it's only when on wifi, or when-charging (or both).
Given about 90%+ of mobile users have access to a wifi point + charger on a nightly basis, this seems reasonable.
I'd mainly use it for podcasts and Audible - keep my casts and books updated so I don't have to sit in the car for 5min downloading the daily selections.
The app autoupdate will do that on its own if you're not careful about disabling using 3g for downloads.
That said I also played a ton of the radio last month too but I wish I could turn 3g for the radio stuff and not the rest instead of toggling it all the time.
This sort of behavior is one of the primary causes of battery drain on Android systems, so yeah, it won't at all surprise me when certain apps start getting fingered as battery hogs.
Don't worry, HN is about to tell you how apple has magically solved this problem in exactly the same way android did, but how it's different because apple did it!
