We experienced an unexpected outage of the site this morning.
Cause is being investigated, but for now it seems the site is back up and working. Please let us know if you have any issues.
Note: you may need to have your browser ignore its cache (e.g. refresh with Ctrl+F5) and bring down everything fresh.
FWIW, system came back up after we rebooted neon (using the Linode manager page), and then bounced varnishd on fluorine and hydrogen (/home/bog/bin/bounce on each.)