While I haven't found voice commands so useful that I prefer it to typing out my searches; still the day will come when voice recognition will overtake physical typing. And leading the pack are Apple Siri and Google Voice. For each, the win will likely lead to more ad revenue and greater information about the user, enabling more targeted advertising.
The use of voice recognition will matter in many ways we use our devices; not just in asking for directions or information, but in having our words dictated on documents. Less typing, more talking. Of course that is fine in a quiet area; I'd hate to be exposed to all that talking while on my train to and from work. Perhaps the next leap will be not even having to say it, but simply think the task and have our devices sync to our brain waves. Science fiction or future science fact.