BuddyPress.org

== Is it possible to just install a new version of buddypress on each subsite so each subsite will have its own version of buddypress? ==

If you install WP at http://www.yoursite.com/ and go multisite – either http://yoursite.com/subsite1 (for subdirectory) or http://subsite1.yoursite.com/ (for subdomain) – that subsite is what’s meant by a secondary blog. And that brings us back that there can be only one BP instance in main site or subsite of a multisite installation.