There's an interesting interview on zdnet from yesterday where Bill Gates talks about many things. Speech is one of them. Here's what he had to say:

This morning, you were speaking about some of the tough problems that software hasn't solved--speech recognition, security, presence. What's holding us back from solving those problems?
Gates: The pace of software innovation today is as fast as it has ever been. In speech recognition, over the past decade, the error rates have come down, down, down, down. Now, we haven't hit that magic threshold where speech recognition is better than the keyboard. It's hard to pick a date where it will be. We totally believe speech recognition will go mainstream somewhere over the next decade. When you use your phone, speech will be your primary input technique. At your desktop, it will be a mix of speech, keyboard and pen.

Our money is where our mouth is. It's like IPTV. I said over a decade ago that would happen. It took longer than I expected, but I'm sure glad we got in early and put the money behind it. I feel the same way about speech. It will be mainstream.