Separately, Google filed a patent application in the mobile space that appears to be about delivering calls vs. clicks to advertisers from a mobile device. Not being an engineer or a patent attorney, it's challenging to read these things and comprehend their full scope. But it would seem to be about implementing PPCall from wireless as an ad model.
Gary Price at Search Engine Watch Blog has more, including a link to the patent app. itself (makes for some nice bedtime reading).
Updated: Google personalized home page for mobile