Well, it doesn't quite work in the sense that you are used to with a PC but there can be multiple apps open at once on the iPad. The catch is that only one can be currently loaded on the screen per say at one time. You can used a four finger sideways swipe gesture to cycle between open apps. Or, a four finger up swipe will reveal what apps are open across the bottom of the screen. Tap whatever app you want activated. Also, when you close an app using the five finger pinch, they technically stay running.
Hope that helps. It's one of those apple things that us PC users have to get used to and it doesn't really work the way we expect it to.
