In the early beta versions of iOS 4.3, Apple enabled “multitasking gestures” on the iPad. Rumors suggested that Apple was considering removing the home button from iDevices, and replacing it with 4 and 5-finger gestures to close and switch apps. The chances of this actually happening are pretty slim, but the code is still floating around in the final version of 4.3. To regain the option, users can purchase Xcode 4 from the Mac App Store ($5), connect an iPad or iPad 2, and enable the “use for development” option (when prompted, ignore the request for developer credentials). Once dev-mode is activated, a new option for toggling “Multitasking Gestures” will appear under Settings -> General.
The free Xcode 3—available online or via the OS X install disk—works as well, but you may need to have a free Apple developer account for the trick to work.