You may already know how to close multitasking apps (a.k.a. background apps) on iPhone running iOS 4.
Presently, you can only close multitasking app one at a time. Some of you wonder if iPhone offers a way to close all background apps simply by a single tap.
There is no such app on App Store. But if you are using a jaiilbroken iPhone, there is a hack called “Remove Background”, which is an add-on for SBSettings. With the hack, you can simply launch SBSettings and tap “RemoveBG” button to close all apps running in background.