ANY speaking course - Carnegie, Toastmasters, voice training, improv theater, whatever - is going to improve your public speaking. It was improv that flipped the switch for me, from being nervous in front of people, to being comfortable on stage, alone, with nothing but a microphone in my hands. In the end, people think confidence comes from knowing the material well. I can say from experience that knowing the material is the smallest part of being confident on stage. There are no real "tricks" to it (imagining the audience naked, for example), it is simply a development of your own internal thinking processes and resources. Practice is the key. And improv. That helps, too.
I'll certainly keep an eye out for opportunities to practice. Which reminds me... Wow. Yep. So I just checked one of the classes that sounded vaguely interesting to me that I registered for. "Creating Communities of Action" wherein: "Explorations and exercises in structured and improvisational theatre games to empower students as facilitators in a variety of fields to build classroom, work-related and community-based ensembles for enhanced learning and productivity outcomes." That sounds perfect. I'm really excited now.