Just managed to view their status page. It's a DOS attack
Major DNS DOS attack
Posted 1 hour, 59 minutes ago (April 8th, 2007 at 1:29 am PST) by micah
Severity: High Resolved: No
We are currently experiencing intermittent DNS outages on all of our nameservers, this is causing problems with sites and email functioning properly.
We think it might be the DNS load balancers we’ve recently installed but haven’t determined that for sure yet. More information will be posted as we have it.
Our apologies for the inconvenience this causes.
UPDATE (2007-04-08 03:20 PDT): It appears we are the victims of an Easter DOS attack against our nameservers, we have an admin at the datacenter and our network expert onhand to deal with it. Hopefully things will be back to normal shortly.
Happy DreamHost Does-Not-Sleep Team!