Say something like "Chinese restaurant," and the app will mark relevant hits on a map, on a list, or produce an augmented reality view using your iPhone camera, pointing you in the right direction.
Speak4it does things that Siri, Google and others do, but the execution is great and it certainly beats typing. Speak4it also has a unique feature where you can draw a circle on the map and the app will show businesses just within that area. If you draw a line, it will find places along that route.
Speak4it is not the best of breed, and certainly not the worst. It has a few unique features that make it worth having in your bag of iPhone tricks. The app is universal, and works quite well on the iPad, but of course there is no camera for augmented reality views.
In my tests the AT&T voice recognition worked just fine, understanding "Hotels near the Phoenix Airport" or "coffee shops near me." The app isn't perfect. It crashed a few times when I pushed the button to see a list view. Perhaps it's an iOS 4 issue. Note: This app works in the U.S. only.
The developers would love for us to point out that Speak4it is not an 'official' AT&T release but comes from AT&T Labs and AT&T Interactive Applied Research. They also note that is is the only iPhone app they know of that performs 'multimodal' integration of speech and gesture.