Back in my day...
Apple would kick your app from the Store for even acknowledging that there was a system underneath.
My, how things have changed.
Android devices have a memory manager utility that can show you which apps and services are running in the background, and allow you to shut them down in order to free up some extra memory. XSysInfo XSysInfo XSysInfo provides more data than iOS 4's multitasking menu, including apps' impact on battery life (right) Apple …
...doesn't one then simply press-&-hold an icon to invoke the delete-jigglies, and then one can close as many background apps as one wishes?
I tend to perform this clean-up function at least once a day to close many dozens of apps that may or may not still be running in the background. Especially if I've been streaming media over 3G - I want to make sure that is really turned-off when I'm done with it. This clean-up must do something since an app that is closed is removed from the background app scroll bar.