Slate has this paean to the Dvorak keyboard layout, something I'd been planning to write for MemeMachineGo! myself, but the Slate article is pretty good, so I'll let it do most of the heavy lifting.
In short, Dvorak is simply better. I've been typing with it for a couple of years now. Yes, the transition took a couple of months and was annoying (my high school required a typing class; I was an excellent QWERTY touch typist.) Though all the typing speed records have been set with Dvorak keyboards, it's probably not the case that you'll notice a speed improvement in daily use.
What you will notice is greater comfort and less fatigue. Since becoming a Dvorak touch typist, I notice when tying a word conspicously involves fingers travelling from the home row. Noticing this with the QWERTY layout would be redundant: nearly every word involves such conspicous travel. To type 'the', I just depress my right middle, right index, and left middle fingers where they sit. In QWERTY, every character involves a reach.
It's easy to logically remap your keyboard in all modern operating systems. And if, like me, you never bother to label the keys or physically remap the keycaps, it becomes a security measure and a source of amusement whenever anyone else wants to do anything with your computer! There is much fuss about computer ergonomics; this is something you can do for free with your existing equipment that'll make a bigger difference than a lot of devices.
One thing I find interesting in talking about Dvorak is the violent reaction it inspires in some. Some people have used Dvorak to demonstrate the limitations of the Invisible Hand of the Market: something obviously superior lost out to something obviously inferior -- QWERTY wasn't even intended to make typing efficient or comfortable: its design goal, explicitly, was to prevent typewriter jams by slowing down the rate at which the physical keys hit the platen. It was designed to facilitate a machine's operation, not a human's use of a machine.
But there are others so dogmatically devoted to the infallibility of the Invisible Hand that this is an unconscionable heresy. In their reality tunnel, August Dvorak becomes an evil, twisted fraud faking his studies. Because, after all, QWERTY has won in the marketplace, therefore Dvorak must not be better. Any alternative is like saying pigs can fly and dogs live in trees.
I think this gets down to a fundamental and pervasive misunderstanding of Darwinism. A free market would be Darwinistic. But Darwinism is not, as is popularly believed, a meritocracy. And this rant has already gained too much momentum to halt, but would go beyond the scope of this entry so I'll give it its own.