The attached patch contains the probes (originally came from Theo
Schlossnagle) that were removed from the previous submitted patch.
Zdenek had some concerns about the way the probes were implemented
http://archives.postgresql.org/pgsql-hackers/2008-07/msg01168.php. If
there are specific recommendations, I'd be more than happy to make the
changes and get them resubmitted.
-Robert