I sometimes complain about the use of video in place of written description, but this screencase is superb: Use Google Mobile for the iPhone for Quick Local Lookups.
There's a link to an earlier Google Mobile review that describes the service in more detail.
Superb stuff. Now if Google Mobile would only allow me to switch between my gmail and Google App personae ...
My iPhone is pretty much a gPhone at the moment -- I use Gmail IMAP with iPhone mail.app, Google Maps, and Google Mobile (fantastic). I'm very much hoping Google will introduce a gCal solution for the iPhone -- the current calendar view is a limited read-only list of appointments. I've just about given up on MobileMe.