I've never seen a jail broken tweak to move the dock to the side. However, there is a Cydia tweak called Deck that allows you to view apps on the sides of the iPad (or the top/bottom, whichever you choose). The dock won't disappear, but you'd have access on the sides. Here is a picture of what I mean (it's from my iPhone, but it would be the same on the iPad):
But, yeah - anything like this is only possible on a jail broken device. There's nothing like it for the stock iPad.