I can vouch for the effectiveness of Toastmasters in addressing the problems the article describes in the first paragraph of "this is Paul Graham". http://www.toastmasters.org/

The rest of the paragraphs in that section are off. I didn't see the presentation, but just reading the writer's complaints about unanswered questions tells me that pg's speech was effective. The goal was to get the audience to want the answers to those questions.