iOS 4.3 Beta has added myriad of cool multi touch gestures for iPad, but Apple has enabled it by default and needs to be enabled manually. As it is a Beta version, you will require Xcode on your Mac to do it. First download the iOS 4.3 and install it on your iPad.
Then download Xcode from the Apple’s website. Open Xcode and click on iPad icon (sidebar). Now click, "Use for Development". You will now be required to enter your Apple Developer user credentials. iPad icon will now turn green. Close Xcode and close Settings.app on your iPad (if it running in the background). That is it. Open Settings on your iPad and go to General tab. You will now find "multitasking gestures" option (and is already enabled).