When MW 1.20.6 came out, I decided to upgrade to it from 1.20.5, and I decided to run the web updater afterwards.
All I got was a blank screen no matter what I tried, so I reverted back to 1.20.5 and everything was normal again.
I'm not sure what happened, but I thought I'd let everyone on the mailing list know that there might be a problem with the newest security release.
P.S. - Not really related to the above, but still MediaWiki related: Does anyone know what happened to the MediaWiki Users forum? It's been down for awhile, apparently due to database issues, and I was wondering if anyone here has more information on what happened.