BuddyPress.org

Create copy of page.php rename to either community.php or buddypress.php open and edit the file to remove one or other of the get sidebars or dynamic sidebar calls depending on how the themes doing things.

BP will use this new file rather than page.php, WP will continue to use page.php where required.

I have drafted a codex page explaining basic theme compat usage with themes but some re-ordering needs doing with the codex before any more pages can be added.