I don’t know much more about these efforts than what I read online, but they represent an interesting confluence:

• From Idealist.org: “The big day is almost here! We’re just about ready to launch the Idealist network—a new online and on-the-ground platform that will help people everywhere take action on the issues they care about. More than 20,000 people are set to learn more and join us [on] March 11 …. We’ll start with a live online presentation, take your questions, and then start building this network with you. Here’s some background about why we’re doing this, and why we need your voice in the conversation.”
• From Rich Harwood: “I’m glad to announce today [Feb. 19] The Harwood Institute’s plan to train 5,000 new Public Innovators by 2016. Public innovators are individuals with the mindset and skills to catalyze and drive productive change in communities and change how communities work together. We’ll also grow our Public Innovators Corps to 100,000 members – individuals who actively support this new direction and use our approach to better their communities, organizations and lives.”

Assuming no overlap, that would be 120,000 people. I admire the scale of these efforts. Of course, there are many more people already at work in civic networks–but additions are always welcome.