Last modified: 2010-05-15 15:48:20 UTC
When I go the user page of a user whose name contains "+", MediaWiki renders the userpage name with a space instead of "+". There is no contributions link. Manually entering the user's name with "% 2B" instead of the plus sign, or entering the user's name verbatim, into the contributions page (see URL) brings up an empty list.
Seems to be solved in 1.10.
This is most likely a local configuration issue with Apache mod_rewrite rules, due to Apache's double-unescaping and broken escaping rules.