AppleInsider has a nice long preview of the new Leopard Dock, along with a short history going all the way back to a company called Acorn Computers, and the NeXT Dock (there's even some good, healthy Windows TaskBar bashing thrown in the mix).
There isn't really anything new here, but it is a nice wrap up of everything we've seen about the Dock so far, including the new perspective that folks are so worked up about, and the idea of "stacks," special icons that will expand into a number of different icons. AppleInsider even runs down the default stacks provided with Leopard-- Applications, Documents and Downloads. I'm not sure how long those will last on my Leopard install, however-- I'm much more eager to make my own stacks and reorganize everything myself.
Very exciting. Unfortunately there's no mention of an update to how the vertical Dock looks, but Leopard is right around the corner, so we'll find out for sure very soon if Apple's new Dock lives up to expectations.