Kleiner Perkins, the well-known venture capital firm that backed Google, Netscape, Sun, Amazon and many others, has always had a soft spot for politics.

In the latest move to add a big-name nationally known star to its outfit, the firm has added Nobel laureate Al Gore as a partner — in an continued effort to ramp up its investments in the area of green technology.

The move follows other high-profile hires, such as former Secretary of State Colin Powell, and an arrangement where former California politician Steve Westly also works out of a back office. However, its unknown exactly how much these people really spend working daily on deals. We’ve hardly heard anything about Powell’s activities with the firm, for example.

There’s an exclusive story in Fortune about Gore’s move, which contains a detailed description of the collaboration between Gore and Kleiner’s leading partner John Doerr. Here’s just the starting snippet:

After “a conversation that’s gone on for a year and a half,” according to Gore, he has decided to join his old pal [Kleiner Partner] John Doerr as an active, hands-on partner at Kleiner Perkins, Silicon Valley’s preeminent venture firm.

The move is more than another Colin Powell moment (the former Secretary of State signed on as a Kleiner “strategic limited partner” two years ago and has hardly been heard from since). Gore is joining the firm as Kleiner makes a risky move beyond information technology and health-care investing into the fast-growing and increasingly competitive arena of “clean technology.”

According to Doerr, by 2009 more than a third of Kleiner’s latest fund, which was raised in 2006 and totals $600 million, will be invested in technologies that aim to reduce emissions of carbon dioxide. Already Kleiner has invested more than $270 million from various funds in 26 companies that make everything from microbes that scrub old oil wells to electric cars to noncorn ethanol. Twelve of Kleiner’s 22 partners now spend some or all of their time on green investments.

Doerr, in turn will join the advisory board of Generation Investment Management, the $1 billion investment company Gore started three years ago in London with David Blood — to invest in publicly traded “sustainable” companies.

[in photo above, courtesy of Forbes, is from left, Blood, Gore and Doerr]