Ha, the blackout is a javascript powered blackout. No reason to bother text browser users, they won't notice the disruption in the first place!
Please don't remove $wgSiteNotice from Mediawiki. It's the only way we http://www.mediawiki.org/wiki/Manual:Wiki_family administrators can with one edit to LocalSettings.php put a notice on our many wikis, without editing each MediaWiki:Sitenotice etc. database changing operations.
DG> http://stats.wikimedia.org/wikimedia/squids/SquidReportClients.htm That table looks horrible in text browsers.