Rackspace’s increasingly popular Rackspace Cloud product suffered a major outage Monday night, taking down a range of popular sites and services.

Sites reported to be down included Posterous (and by extension Robert Scoble), Tr.im, a range of smaller Twitter tools, and of course we were offline for the best part of an hour as well.

Rackspace said in a support update that they had experienced a power issue with their Dallas data center. An attempt to reach Rackspace’s “fanatical support” when the service first went down resulted in nothing more than a busy message.

The outage also affected Slicehost (which was acquired by Rackspace last year), Laughing Squid and a range of smaller Rackspace resellers.