On my fifth and final attempt, which was also a success, I gave my ZIP code when it prompted me for my city and state. It correctly identified my city. I then said "Starbucks," and it came up with the closest one in the area. When it offered to connect me or provide me details, I said "text message." The service immediately disconnected me, without a word of confirmation or farewell -- but seconds later, I indeed received a text with the address and number of the Starbucks. That's pretty slick.
While there are some neat features here, the service needs some work. The fact that it was swamped and that it disconnected me twice suggests Google is having problems on the back end. Maybe the company wasn't expecting its service to be so successful. Also, the voice recognition might just need some tweaking (or else I need to work on my enunciation if, indeed, I pronounce "sushi" as "fishing").
Also, the computerized voice that helps you is a bit grating and talks too quickly when rattling off a business name. Moreover, unless you've done some research in advance, you won't know that you can give a ZIP instead of a city or state, that you can key in information instead of saying it, or that you can request a text message.
Technical issues aside, it will be interesting to see where Google takes this service once it's perfected. The GOOG-411 FAQ says that advertising opportunities aren't currently available, though one wonders if that will change. Will companies be able to pay a premium to be the top listing when Bob calls up asking for "pizza" or "fishing gear"?
And at a higher level, what does Google have to gain from this? Well, it's a means of further enhancing its search services, of course, making it an even more compelling one-stop shop for all your information needs, both from the desktop and on the go. The "map it" has obvious utility, in case you don't have the time or the free hands to do a search yourself on your mobile device (if, for example, you're driving.)
I also imagine scenarios where a user with a smart phone looks up a business through Google on his or her mobile Web browser, then clicks a "call it" feature to connect and talk, rather than dialing the digits him- or herself.