I could go either way on a new Jetty upgrade: 1) The current version has been tested for a year with this specific application (Solr) and thus it's less risky sticking with it, esp since we haven't seen any problems. 2) Many bugs have been fixed in the latest patch release of Jetty... and just because we don't think we've encountered bugs in the old version doesn't mean that others won't.
IMO, If we don't upgrade now, it makes sense to upgrade immediately after a 1.3 release. -Yonik