Google’s CEO is “bullish” on mobile advertising. If he doesn’t want to see Google’s stock go into free fall—it’s lost about $42 billion since the new year—it had better be bullish and right. Google’s future is tied to getting ads on more places besides PCs and the mobile phone is the obvious place. You’ve heard it before—everyone has one, they’ve got screens and many—and soon most—will have internet connections. But lots must happen for mobile ads to kick in. For one, there has to be stuff on the mobile phone that attracts eyeballs. That requires a healthy mobile ecosystem emerging—as I noted in my CTIA presentation “Marketing the Mobile Channel”–and we’re a ways away from that in the US.

Maybe Google is bullish because it has decided that it is going to be the catalyst. Beyond that, Google will need ads that make sense on the little screen. As the FaceBook ad fiasco has shown, you just can’t assume that what’s worked in one setting will work in another. I’m sure there’s a bunch of supersmart 23 year olds working on that right now at Google.

Anyone who knows what’s happened in Japan and Korea knows the immense possibilities of the mobile phone attracting eyeballs to the Internet. They’ve gotten there faster because it was easier to get the incentives aligned in their ecosystems—and because of the profound idiosyncracies of those societies. I’m certain the mobile phone is going to be killer in the US and there’ll be lots of money to be made on ads. It’s real hard to say whether that’s 5 years out, 10 years out, or longer.