It shows a cross-platform web application with main items draggable up and down on the page, todo items draggable within and between todo lists, and images draggable horizontally. Part of making it work well involves showing drag handles only when elements are hovered over. This is a really clever way to stretch the limits of browser technology.
What it really shows, though, is that a small company with only a few great hackers can do things that are just as impressive as what hundreds of Googlers can do in building GMail. And I bet they did it in a tenth of the amount of code.
I just don’t think a business person could commission anyone to come out with something like the new version of BackPack. It’s too creative for it to be done just by throwing lots of money at the problem.