Let me update this: we've been working all day on moving Trello to AWS, a project which is now underway. If all goes well (fingers crossed, etc) we'll be up and running on AWS very soon. There are still other services in the flooded New York data center (FogBugz, Kiln, Copilot) and we are making plans to physically move servers to a new data center as quickly as possible if the flooded data center falls over, but a physical move of 5 racks could take a whole day so I hope that doesn't happen.

Separately, Stack Exchange, which is in the same data center, is running off of its hot backup in Oregon.

We would have liked to have completely redundant data centers for FogBugz on Demand and Kiln on Demand to avoid even a few hours of downtime, but because those services rely heavily on giving every customer their own SQL database, there is almost no reasonable way to get fast failover to a different data center. We can do it with Stack Exchange because there are only a couple of hundred databases. We've been building a SAN solution which will make it possible to hot swap out to another datacenter, one day, but that project is not complete.