A client-side solution could be nice. I suspect the site performance would suffer if a couple dozen additional "scripts" were being parsed by the server every other page load. There are some decent JS syntax highlighters. Maybe we could have something like Chili available through user settings. It wouldn't do as correct a job on the markup as PPI but it could still be nice and does decent markup on a variety of other languages which get posted too (XHTML, Java, JavaScript, SQL, etc). Would have the side-effect of making jQuery available on the site which would open up many other possibilities; if desired.