At this moment, the Joomlaboard integration is the best.
Yes you need to install it separately.
Vbulletin and SMF bridges are present for Joomla but no integration with CB yet.
After installing CB 1.0 RC2 your backend Components->Community Builder->Tab Management should have 2 forum related tabs. One is titled 'Forum Settings' and is used to alter various forum related settings (signature, etc) in the front-end when updating your profile (assuming of course that you have installed joomlaboard/simpleboard component). The other is titled 'Forum' and is used to display the last posts in the forum (again we assume that the forum component has been installed). These 2 tabs should be published.
Also in the Plugin management you should have a plugin titled 'Simpleboard Forum'. This should be published.