BuddyPress is essentially a set of WordPress MU specific plugins. Each plugin component adds a distinct feature to BuddyPress and only handles functionality for that specific component (for example, private messaging). BuddyPress also has a core plugin that all other plugins require, it contains shared functions and performs the basic modifications to the WordPress MU interface.
Tune into the show to hear Andy Peatling delve into the feature set of the project as well as taking questions from the audience. By the way, if you don’t have the ability to install WordPress MU and then BuddyPress, you can view and participate in a live demo by registering an account on http://www.testbp.org