This seems to be a power outage at our European proxy caching cluster; Mark may be able to provide some more details.
European traffic has been rerouted to our US servers, but the extra load may cause the sites to be a little sluggish for now.
(If your DNS is still seeing the old entries, you can manually configure your browser to use the US proxy: rr.pmtpa.wikimedia.org port 80. You should only do this temporarily, as you won’t be able to access anything *but* Wikipedia and our sister projects. :)
Also posted on tech blog: http://techblog.wikimedia.org/2009/07/power-outage-in-wikimedias-european-se...
-- brion