Originally Posted by rawness
That's a loaded statement that's not necessarily true. For example, there are some apps that when exited (or exited in a certain fashion) still run GPS. Now, sure, you could add an app to turn off GPS, but then you'd have to remember to re-enable it when you open an app that uses. Some people, understandably, don't want to keep a mental tab on their GPS setting.
Correct. I was more or less referring to the memory that open apps use, not so much the radios. Leaving an app open that leaves the GPS/Wifi/BlueTooth radio on will definitely drain the battery.