Buddypress Add a Facebook Like/Unlike button to activity stream items.

buddypress-facebook-like.php

/**
* bp_like_button()
*
* Outputs the Facebook 'Like/Unlike' .
*
*/
function bp_like_button( $id = '', $type = '' ) {
    $activity_permalink =  bp_get_activity_thread_permalink();
   ;
 ?>
 <!-- your iframe code, replace href=http://www.link_used_for_generation.com   by href=<?php echo  echo $activity_permalink; ?>  -->
<?php
}
add_filter( 'bp_activity_entry_meta', 'bp_like_button' );