I have produced this video demonstrating the new four finger gesture multitasking technique added to iOS 4.3
I start with the traditional double-click method of opening the Multitask ribbon. The list of currently running iPad applications is shown.
I then demonstrate use of the “four finger” technique to swap running applications on the iPad. Swiping left to right, and up and down methods are demonstrated. Enjoy the video!
UPDATE: Some users are reporting they cannot perform these actions after their iOS 4.3 update. If this is the case on your iPad, open the Settings application, select General and toggle the Multitasking Gestures switch to the ON position.
UPDATE 2 (03/11/2011): After sampling Apple store demo iPads, I found out currently the multitasking feature is limited to those with Apple Developer membership.