I think is important to check field's visibility before showing the button, so I modified the facebook-members-extension.php file, by replacing the line 27, with this:
<?php if ( bp_current_user_can( 'bp_xprofile_get_privacy_levels' ) ) : ?> <a class="bp-fb-profile" target="_blank" href="<?php echo $fbcj_username; ?>" ><img src="<?php bloginfo('wpurl'); ?>/wp-content/plugins/buddypress-facebook/img/facebook_social.gif" /></a> <?php endif ?>
I also added the target="_blank", maybe this should be an option in plugin settings or just added by default to open in new tab/window.
Great plugin, thanks, Samuel Costa!
This could be easily be extended for others social networks... LinkedIn, Twitter, G+...