I've read somewhere, I can't seem to find it now, that in an experiment involving people learning to type, that the Dvorak keyboard didn't have a tangible typing speed benefit in comparison to the QWERTY keyboard. Do you know of any studies about this?
Somewhat. Typists can, in fact, learn to type faster on a Dvorak keyboard, it's just not a big improvement.
The Dvorak typewriter keyboard was found to produce speeds of keying 4.0 percent faster than those of the Standard (Qwerty) keyboard. However, employers were reported to be unwilling to bear the costs of the several weeks required to retrain employees on the novel keyboard.
Even in The Fable of the Keys, a paper whose authors seem to have an axe to grind, admit that (full citations for these can be found in the paper):
In two studies based on analysis of hand-and-finger motions R. F. Nickells Jr. finds that Dvorak is 6.2 percent faster than Qwerty, and R. Kinkhead finds only a 2.3 percent advantage for Dvorak. Simulation studies by Donald Norman and David Rumelhart find similar results.
So there is a speed improvement to the Dvorak keyboard over the QWERTY keyboard. It's just not a very big one.