As promised, here is a video of how to install the new iPad multitasking gestures that were in the iOS 4.3 Beta. To do this you simply have to to download and install xCode 4 from the Mac App Store. xCode will run you $4.99 so be sure you really want these gestures, it's like paying for a tweak, not that xCode isn't useful.
Once you have downloaded the 4 GB+ file, install it, and plug your iPad in. Now go to your iPad tab in xCode and click "Use For Developement". xCode will enable Development Mode on your device and now you have the new gestures(you can turn them off in Settings-General).
If an easy, free, way come out on how to do this, we'll be sure to keep you posted.