Joomunity is already light years ahead of community builder and still has a lot of potential. The only drawback is that it's still in beta and many areas are lacking polish. I am currently implementing it on a social site I am building but it's not something I'm ready to show off. If you'd like to see Joomunity in action, you can either create an account at
www.joomunity.org
or login with their demo account. I can confirm that everything works the way it does on their site. And a bit of advice if you choose to install Joomunity. Make sure you have the latest version of PHP running on your host and you may have to install it manually since the auto-installers don't always work.