The initial prototype used f and j for the up and down motion of the right pointer finger. This was simple done as f and j are the first letters in the typing trainer that I use. The layout of the keys will be important. No firm plans have been made, and certainly things will likely change in testing (they always do). The basic idea is to leverage fingers that are more versatile and motions that are most comfortable.

This image from the Wikipedia Letter Frequency post gives us most of the info that we will need. There are 9 very common letters. Those should be given prominent positions. In addition, the space bar, and backspace are very commonly used buttons.

http://en.wikipedia.org/wiki/Letter_frequency