Possibly because of Sandy - Squarespace, which runs the back end - is in New York.
I think I can wait out the storm (so to speak) and will chase them up later - in the mean time any of the links you see are broken so don't bother clicking on them.
Except this one: hopefully it'll work and you can see what they're up to.
UPDATE: No, even that one. Head over to status.squarespace.com if you want to see what they're up to.