How can I detect whether a BuddyPress page is active from within my theme?

EDIT: I received a direct, easy answer from the folks over on the BuddyPress forums:

There is a template tag called bp_current_component() that returns a boolean. So, in short, to tell if we’re currently in a BuddyPress-ized section of the site, we simply call:

if( bp_current_component() ){

…or, if we want to detect when we’re NOT in a BuddyPress area, the inverse:

if( !bp_current_component() ){

Easy peasy.

So, in total, the code looks like this:

if( !bp_current_component() ){
    if ( is_page() ) {
        if( empty( $wp_query->post->post_parent ) ) {
            $parent = $wp_query->post->ID;
        } else {
            $parent = $wp_query->post->post_parent;
        }

        if( wp_list_pages( "title_li=&child_of=$parent&echo=0" ) ) { 
            echo '<ul id="subnav">';
            wp_list_pages( "title_li=&child_of=$parent&echo=1" );
            echo '</ul>';
        }
    }
} else {
    echo '<ul id="subnav">';
    if ( is_user_logged_in() ){
        bp_get_loggedin_user_nav();         
    } else {
        bp_get_displayed_user_nav();
    }
    echo '</ul>';
}