LinkedIn founder Reid Hoffman and Bill Gates team up for a $30 million investment in petition site Change.org (MSFT)

Steve Jennings/Getty Images LinkedIn cofounder Reid Hoffman is leading a $30 million investment in Change.org, the for-profit"social change platform" that's best known as a site for activists to post petitions to the public. Hoffman revealed that he'll be leading the round in a post to LinkedIn, with Fortune reporting that Microsoft cofounder Bill Gates and Y Combinator President Sam Altman will also be participating. All three tech leaders actually participated in the company's last $24 million...