So you’re 37, and you’ve taken on this mentoring role to people like Facebook’s Mark Zuckerberg and other entrepreneurs.

There’s a new generation of entrepreneurs in the Valley who have arrived since 2000, after the dotcom bust. They’re completely fearless.

Does that create the danger of a new tech bubble?

If there’s been a crisis in a market, you don’t tend to have a new crisis in that market until the people who went through the last crisis aren’t in the system anymore. It was only eight years ago. So here we are in 2008, and there’s still no sign of a bubble in technology, which I can encapsulate in two words: no I.P.O.’s.

No tech I.P.O.’s—is that a good thing or a bad thing?

Well, a very important thing. Through the 1980s and ’90s, tech companies would basically get into their expansion stage and then go public. In part, it was to have access to capital, in part to have an M&A currency, in part as a branding and a credibility event, and in part because there was a base of investors who wanted to invest in high-growth technology companies. Those days are just over. It’s just frozen. Is it a crisis in terms of company formation? Not yet.

We haven’t talked at all about mobile internet.

There was mobile before this thing [holds up an iPhone], and then there’s mobile after. If you were trying to build software for mobile phones last year, you were in a world of pain, of incompatibility—you had probably seven different operating-system platforms you had to deal with. You didn’t have any way to do over-the-air distribution of software or content. The carriers, especially in the U.S., had a choke hold on distribution and would put up huge barriers. It was an absolute nightmare.

As of now, that hasn’t changed.

That hasn’t changed, unless you’re on an iPhone. The iPhone is going to be at 100 million units before you know it. This is going to force everybody else to raise their game.

Is Google the new Microsoft—the new big, scary, monster company in tech?

It is true that Google is doing a lot of different things, and some will compete with other Valley companies. But the pros outweigh any future competitive threat. Google does so much to make other startups possible. Google makes new internet efforts easy to find. Google runs a large advertising network that distributes money to people who run ads. It is training and educating a very large base of really sharp people, many straight out of college, many of whom are not going to spend their entire careers at Google. Google is fertilizing the base. So I think it’s been very, very positive.

How about all the fears that Google is too powerful?

I don’t see it yet—and a big part of why is Google C.E.O. Eric Schmidt. Eric literally does not want to run a company whose M.O. is to just gratuitously go around and stomp on people.

You’ve probably got a good 30 to 40 years left in the business. What do you ultimately want to accomplish?

I love what the Valley does. I love company building. I love startups. I love technology companies. I love new technology. I love this process of invention. Being able to participate in that as a founder and a product creator, or as an investor or a board member, I just find that hugely satisfying. And I think the outcome can be big and important and profound.

I hear you’re getting deeper into philanthropy—Stanford Hospital, Room to Read.

That is increasingly important to me, for a couple different reasons. Partly, it’s wanting to give back. And partly, my wife of almost two years teaches philanthropy at Stanford. So I am completely committed to philanthropy because if I’m not, I’m in a great deal of trouble. I can’t even tell you.