The version 1.0 release can be downloaded right now, or you can choose for the Pro version which gives you a number of extra features. It's available for Windows XP, Vista, and 7, with versions for Mac OS X and Linux in the pipeline. The best way to give you an idea of how BumpTop works is to watch this little vide, that more or less gives you all you need to know.
After using BumpTop for a while, a few things become obvious. Let's get the good out of the way first: it's fun. Throwing your files around, stashing them into piles, making them bigger, bumping them into one another, pinning them to the walls - it's all very entertaining. Performance is a bit slow at the moment (AMD Phenom 4x2.2Ghz/4GB of RAM/Radeon HD 3200), but I'll forgive them that since it's just their first official release.
Still, despite the fun and all, it's very hard for me to actually find it useful, and that mostly stems from the fact that it seems as if BumpTop is a bit ahead of the times. It sorely needs a 3D display, but most of all: it needs a 3D input device. You see, all the screens and input devices we use today are 2D, and slapping a 3D interface on top of that is simply a bit cumbersome; it creates perspective issues that mess with your brain. It's like the Leopard dock, but much more obtrusive. Things like windows are also 2D objects, which simply do not fit very well in a 3D environment.
Then there's the issue of whether or not adding a 3rd dimension to computing actually makes computers easier to use. In our very first Common Usability Terms article, on spatial memory, I already touched on 3D interfaces. A study performed by Cockburn & McKenzie (2002) found that there was no benefit to adding a 3rd dimension to user interfaces - in fact, it only made subject's performance deteriorate. They tested both real-world and virtual interfaces, both in 3D as well as "2.5D". Their conclusion:
Getting back to our original question, it's hard to escape the feeling that BumpTop is a gimmick. It suffers from a lack of 3D input and display devices, and the fact that there are indications that adding a 3rd dimension to computer interfaces only makes them harder to use - not easier. It increases complexity instead of reducing it.
Still, that doesn't mean BumpTop is a bad product. It works very well, looks good, and it's a lot of fun. At least they're trying something new, which cannot be said of the big players in the desktop market.