Here’s the announcement by Kleiner Perkins, posted on its Web site today.

Joy has dabbled in investing for quite some time, even having his own investment firm called Highbar Ventures, where he invested with Roy Sardinia and another Sun co-founder Andy Bechtolsheim — so this isn’t entirely a new departure for him. However, Sardinia and Bechtolsheim have both become involved in full-time gigs, leaving Joy without the infrastructure he felt companies really needed from him as an investor. “All of a sudden, I had a lot of really interesting things coming to me that I didn�t have any way of supporting at a level that I wanted too,” Joy tells us. “It’s not about money, but about building great companies.”

He says investing requires a sort of “fellowship of the ring,” where each partner in a venture capital firm works with the others to build the start-ups the firm invests in. The specific partner who joins the board of the start-up is the “bearer of the ring,” he says.

Joy has written about what he sees as the dangers of self-replicating nanotechnology. See here for the Wired article which sparked quite a debate — garnering both fans and critics. Kleiner has invested in nanotechnology, but Kleiner Perkins partner Vinod Khosla has criticized what he sees as too much hype in the sector. Khosla, of course, founded Sun alongside Joy. John Doerr, who recruited Joy, was the original investor in Sun. So it’s a comfy addition.

Note that Publishing Trends once reported that Bill Joy had sold a book idea to Penguin�s Rick Kot for $1.6 million — to be about his views on things like nanotechnology. However, he never got it done because of a mental block. He wrote three drafts, almost 200,000 words, but by then, his original idea conceived in 2000 about how “crazy people can do things” had become almost a cliche, he said. It may have been insightful at the time, but then 9/11 happened, and the New York Times was writing almost on a daily basis about things like terrorism, bioterrorism and so on. “You tear your hair out,” he said, referring to the writing process. “It kills you.” So he realized that he had more to contribute by helping out in science and technology investing, than as a writer or public policy expert: “If we can alleviate some of the suffering, by creating wealth for everyone, it can reduce the pressure for this kind of bad behavior,” he told us.

UPDATE: We tweaked the original entry. Apparently, Bill Joy is not a “venture partner,” as referenced in the WSJ. Any investments he makes, Joy clarified, will be on behalf of Kleiner Perkins, and so he’ll not be making the sort of co-investments that some so-called venture partners make using their own money. We plan to write more about Joy in tomorrow’s paper.