Great article on the possible explosion in the use of voice as input / output for computers.
The privacy of your computer whispering audio cards in your ear can clearly work, although I'm certainly not good at multitasking e.g. listening to a conversation as well as the TV. Will it be more distracting than checking emails on your mobile? Ask a live news presenter, I guess.
Input is still tricky: less private than a quick typed message, much less flexible than direct text and gesture. I'm sure navigational commands will be easy, information and questions less so.