One of the main features of the iOS 5 brought with it is Notification Center which displays useful information to the user without unlocking the screen. Now, with the help of a Cydia tweak, you will be able to kill the running apps as well. This jailbreak tweak is called WeeKillBackground (not we kill background).
Once you have installed it (via Cydia). the tweak adds a button to the pull down menu of Notification Center that lets you close the running apps and processes. This is great for a device like iPhone which does not have a gig of memory like other smartphones in the market. Of course, you will have to jailbreak your iPhone to obtain this tweak.
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