This seems to be a power outage at our European proxy caching cluster; we’ll see if we can give more details later.
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. :)
Update 21:13 UTC:
European servers are coming back online, we should have this cleaned up pretty soon.
Update 21:26 UTC:
We’re starting to switch traffic back to Europe. Should be better in a few minutes… In the meantime, amuse yourself reading the Twitter panic. :)
Update 21:40 UTC:
You can also use the SSL interface to Wikipedia, which doesn’t have the proxy overload.
Brion Vibber, Lead Software Architect