The application adds a "Voice Search" function to the iPhone that allows users to simply talk into the iPhone and then Google will return the results without you having to spend a couple of minutes typing the search query in on the tiny on-screen qwerty keyboard.
The application knows when to start recording your spoken query by the action of you raising the iPhone to the usual phone-holding position. It will then stop recording and fetch the results once you then remove the iPhone away from your face again!
It is interesting to see an application of this sort appearing on the iPhone before it is available on the Google Android phone (I may be wrong here), but it would be nice to hear how successful the voice recognition software involved is. My experience with voice recognition software has not been great, but I have not dabbled too much in it in the last couple of years and suspect some great developments have been made. Although I never expect the software to accurately return "Cu(pyz)(ReO4)2(H2O)2", I always found it had difficulty with some standard words that I could never fathom as to how it managed to get it wrong. For example, I once said "windows" into the microphone on my computer and it typed "ramps"! I gave up after that.
However, as the search query is likely to be 4 or 5 words at most, this software should have an excellent success rate. I particularly like the automatic detection of your location so that a search query along the lines of "movie show times" will give local results. More reasons to add to the list of why I want an iPhone!
Google have posted the following video on YouTube to demonstrate these developments:
Google Voice Search Application for the iPhone