Leah Findlater, Jacob O. Wobbrock, and Daniel Wigdor. 2011. Typing on flat glass: examining ten-finger expert typing patterns on touch surfaces.
This article is interesting, because it seems like if tablets are every going to completely replace laptops, then they will need a better method of entering text. I would love to see if any Android keyboards out there have adopted the design suggestions that this article concluded with, or at least some level of personalization with arced keys. I'd also be interested to see what else Apple is coming out with.