Just got a response from Rackspace; the problem is fixed.
Apparently there was a DDOS attack on Rackspace this morning that took out the load-balancer, and even though it came back on, it wasn't connecting properly.
Sites on *.status.net are off-line because of a blown-out load-balancer. I've got a new load-balancer up and working, but the DNS for *.status.net is still propagating, so many people are still hitting the old one. So: still working to get the old one up and running.
Thanks to the Rackspace Cloud team for helping to get this load-balancer restored.