In the peak of the Internet bubble, a company’s valuation– and press attention– would soar simply by whispering the words “John Doerr is an investor.” But in early Web 2.0 days, the once-everywhere venture capitalist seemed to fall off of the tech press’s radar, at least when it came to Internet investing.

But boy, has Doerr made up for lost time this year: Keynoting both of our Disrupt conferences, holding press conferences at Facebook, and generally leading the charge on the messaging that Kleiner Perkins Caufield & Byers is serious about investing all over this mobile-social wave of digital innovation. The lastest move was his signing of Wall Street analyst Mary Meeker as a Kleiner Perkins partner– a deal he personally negotiated with Meeker, according to an interview we did with both of them this morning.

So I had to ask while I had him on the phone: Whatever happened to Doerr’s belief that cleantech was the next big thing? Don’t worry tree huggers, Al Gore and concerned climate change watchers, he still believes. And like some other VCs, Doerr says that 2011 will be the year believers start to get rewarded. “We still believe there are enormous opportunities in green technologies,” he said. “There will be bigger than billion-dollar IPOs in the next 12-to-18 months. But what’s going on in the Internet is tremendously exciting too. We can walk and chew gum at the same time.” (Meeker laughed and asked whether she was supposed to have done that during the interview process. There’s an all-hands investor retreat for the firm this week. I’m betting Meeker gets a case of gum from someone…)

Kleiner’s clean tech portfolio is here, and it includes a range of big bets like Tesla-competitor Fisker Automotive, regenerative fuel cell maker Bloom Energy, low-cost solar film maker Miasole, and smart-grid technology company Silver Spring Networks.

When I tried to press Doerr on which of these two opportunities he was more excited about, he wriggled out by saying he was most excited about working with Meeker. Yep, looks like the master of working the late-1990s media is back.