Just something to think about: for languages written right-to-left (mainly Hebrew and Arabic and other languages written in those scripts) editing wikitext with markup can get real ugly due to bidirectional text layout in the browser's text editor widget.
Among other things, the on-screen position and direction of punctuation pairs (eg [], {}, and <>) may change depending on whether surrounding text is LTR or RTL. If you're mixing Latin-script keywords and local text together, things start flipping around in interesting ways and it gets hard to tell what's what.
Where keywords are used, making sure it's possible to use localized keywords throughout the system, and being able to isolate necessary Latin keywords (such as CSS style definitions) can make a big difference in usability here.
-- brion vibber (brion @ pobox.com)