Scientific American: Talking to Bill Gates "SA: Some critics have said that there is an unbelievable collection of talent here but that there have not been achievements on the order of things like the transistor. Do you see any validity in that?
BG: Well, we do software. And if you look at the papers at Siggraph [a computer graphics conference] and the proportion coming out of our one lab, you see us in many different areas. We wish there were other labs doing more. We are a very high percentage of the nonuniversity work being done in many of these fields. Typically in the computer field, most of the companies don't have long-term research. They just don't.
Take what we've done in machine translation--no, that's not as good as the transistor, but it's pretty phenomenal. The stuff we're doing with speech, pretty phenomenal. Electronic ink. Software reliability. If we weren't able to prove [test and validate] programs, we wouldn't be able to get the Internet to achieve its potential. An investment of the size we're making will only be judged 20 years from now."
Also worth skimming the full interview (14-page pdf)