TrackbackSwap
Links to a different copy of the trackback CGI if there are no trackbacks on an entry; you can then use robots.txt to tell Google not to index your blank trackbacks
<MTEntryIfAllowPings><a href="<$MTCGIPath$>
<$MTTrackbackSwap$>?__mode=view&entry_id=<$MTEntryID$>
" onClick="OpenTrackback(this.href);return false">
Trackbacks (<$MTEntryTrackbackCount$>)</a></MTEntryIfAllowPings>
