Guys,

I think it will be reasonable to introduce possibility to allow users to show some dummy page in case of DC failover.
They may create this page from Linode webconsole, and in case if, say, Fremont DC is down, your nameserver just redirects requests to that page in other DC. So, we will be able to save our users by informing them that site will be back soon.

Something like DNS fail-over service.