I would consider typing speed to be a positive, desirable quality for a developer. However, it ranks very low on the list of such qualities. For example I would rank creativity, work ethic, desire to learn, knowledge of the languages of choice / development environment, patience, and even humility far above typing speed.
I can type relatively fast (~90wpm) and I will say that this translates into my ability to code as well. When I'm actually writing code, I can spit it out very quickly if I know what I am to write. Couple this with the fact that I use as many shortcuts/macros when writing this code as possible and the code itself comes out very quickly. In fact, when I am helping or watching other developers, I tend to get frustrated at the speed with which they're writing the code (I lack the patience quality, apparently).
Of course, actually writing the code is such an infinitesimally small part of the actual coding process. I think that probably about 95% of the time I am coding is time when I am not typing because I'm thinking about what it is I'm going to type. Couple this with the fact that I undo maybe about 50% of the code I have typed at any given time. Even coding is probably only about 50-60% of my day, so code typing takes up an estimated 1 to 2% of my day. If we say the average typing speed is 45wpm and everyone is typing as fast as possible at all times (including myself), and that everyone's implementation of their projects provide equal benefits, that makes me about 1 to 2% more efficient than the average developer based on typing speed during coding alone. In reality, it is probably about half that.
I think it is very important to point out what happens during the other 40-50% of my day, though. I spend a lot of time composing emails and documentation. In point of fact this takes significantly more typing time than coding, and it certainly has less continuous breaks. This certainly bolsters the efficiency gained from fast typing ability.
To summarize, I would suggest that fast, accurate typing ability should be viewed as positive and earn an applicant some points for development, but only very few. That is to say if everything else is equal, I would pick the faster typist.
In your specific case I would hire this developer if there is no other reason not to besides his typing speed. If he's still typing with two fingers, and slowly, you may even want to suggest that he spend some time trying to improve his speed. You can do this by mocking him continuously (joke), or even train him a bit, but typing training for developers is almost certainly not worth it. You can suggest that he play "Typer Shark" or something on his off time. He doesn't even have to know your ulterior motive of improving his typing..maybe you just like the game.
