The search-by-voice iPhone app we heard about on Friday may not have shown up as planned, but it is now available from the iTunes App Store. The iTunes page itself doesn't show the app as updated, but download and sync it anyway, and you'll notice a shiny new Google Mobile on your iPhone complete with voice-recognition. I've just started playing with it, but my initial one-word review: Amazing!
PS. You'll be please to know that Google Voice detects an iClarified search with no problems :)