The latest WikipediaWeekly podcast spent some time on the need for syntax highlighting (relating to Ben Yates' blog post). http://en.wikipedia.org/wiki/Wikipedia:WikipediaWeekly/Episode62 http://www.enotes.com/blogs/wikipedia/2008-09/wikipedia-needs-syntax-highlig...
As mentioned, the Gadget "wikEd" works quite well for this. (but it is currently for Mozilla-browsers only, and can slow down the response on older machines. Unfortunately, the syntax highlighting is the "most time consuming procedure".) http://en.wikipedia.org/wiki/User:Cacycle/wikEd http://en.wikipedia.org/wiki/Image:WikEd_screenshot.png
There was also Magnus Manske's "less edit clutter" script that separates the different content types, and a slew of other things. http://lists.wikimedia.org/pipermail/wikien-l/2008-March/091978.html http://www.magnusmanske.de/wikipedia/less_page_clutter.png
I've used both on-and-off, and hope they continue to refine and grow.
-- Quiddity