If you consider that you and your users are in some sort of a ‘relationship’, then good communication is pretty important. The Rackspace datacenter outage reminds me yet again that we’re lucky to have a handful of servers in more than one datacenter that can communicate to users in the case where we’ve lost one of them.
Desperate times call for desperate measures, and in the case where you lose a DC, having that $9.95/month webhosting account (or whatever) for serving a status/downtime/blog page somewhere else can sound like a bargain.