I don't know if this affects other wikis, but currently all the remote (full URL) links in the sidebar at mediawiki.org are broken.
For example, the bug tracker link currently points to http://www.mediawiki.org/wiki/Bug_tracker-url, instead of http://bugzilla.wikimedia.org/ (as specified at [[Mediawiki:Bug tracker-url]]).
- Mark Clements (HappyDog)