Please post in this thread if you encounter any issues as a result of the MediaWiki upgrade
we performed on the evening of 2013/01/19 (Pacific Time). To be more specific: if something is now broken (server errors, PHP errors, or downright broken behaviour) which previously worked for you, let us know here. This is not a thread for feature requests!
I'll keep this thread open and marked as an announcement for 2 weeks before removing its announcement status + locking it.
More technical details for those wanting them:
We upgraded from MediaWiki 1.18.0 to 1.20.2. If you want to review all the changes between all minor and major versions, here you go:
And here's the list of currently-known issues for MediaWiki 1.20.x: