Rackspace has had a major power incident at the data center keeping the 37signals suite of machines. Apparently, a traffic accident knocked power out to some vital cooling systems. When the power was restored through generators, the cooling systems failed to come back online.
They now have the cooling systems back up and are getting everything back online. We hope to be back very shortly.
No data has been harmed, the machines were preemptively shut down when the cooling systems failed.
A good number of other applications, such as Wesabe was hit by this as well. Hopefully they'll be back shortly as well.
UPDATE: Everything is back in working order. Read more on the product blog.