IOS 4 Multitasking. Messy and confusing.

Question

So, I am very confused about the multitasking with iOS4. Apple customer service tells me that the apps that are open in the multitasking bridge are not really running in the background eating my phone's battery/memory and that I should not worry about them.
But what about the apps that are? How can you tell which apps are running and which are simply frozen?
For example, imagine I open Pandora and turn down the volume, and then I open a calculator, a game, and a weather app. Now, looking at the bridge there is no way to tell that Pandora is running in the background and the other apps are not. Pandora gets pushed down the list with every app that I open and eventually it would get lost in the shuffle.

Answer 1

To answer specific items in greater detail...
Derek Doublin1 wrote:
So, I am very confused about the multitasking with iOS4. Apple customer service tells me that the apps that are open in the multitasking bridge are not really running in the background eating my phone's battery/memory and that I should not worry about them.
If the app doesn't use one of the 7 'multitasking' APIs then it will be frozen and not use background resources. Of the 7 APIs the one most likely to affect battery life is geolocation and anytime a geolocation app is active there will be a little arrow next to the battery indicator at the top right. The other six (in bold) don't use up a lot of battery compared to geolocation (items below from developer.apple.com):
*Background audio* - Allows your app to play audio continuously. So customers can listen to your app while they surf the web, play games, and more.
*Voice over IP* - Your VoIP apps can now be even better. Users can now receive VoIP calls and have conversations while using another app. Your users can even receive calls when their phones are locked in their pocket.
_Background location_ - Navigation apps can now continue to guide users who are listening to their iPods, or using other apps. iOS 4 also provides a new and battery efficient way to monitor location when users move between cell towers. This is a great way for your social networking apps to keep track of users and their friends' locations.
*Push notifications* - Receive alerts from your remote servers even when your app isn't running.
*Local notifications* - Your app can now alert users of scheduled events and alarms in the background, no servers required.
*Task finishing* - If your app is in mid-task when your customer leaves it, the app can now keep running to finish the task.
*Fast app switching* - All developers should take advantage of this. This will allow users to leave your app and come right back to where they were when they left - no more having to reload the app.
But what about the apps that are? How can you tell which apps are running and which are simply frozen?
Normally you would find that in the programs documentation or look at the above 7 and see which it must use to work properly.
For example, imagine I open Pandora and turn down the volume, and then I open a calculator, a game, and a weather app. Now, looking at the bridge there is no way to tell that Pandora is running in the background and the other apps are not. Pandora gets pushed down the list with every app that I open and eventually it would get lost in the shuffle.
If Pandora is in the bar it is running and presenting audio unless you paused Pandora before turning the volume down. Would it still use the Audio API when paused and exited with the home key? I doubt it, but I really don't know.