This sounds like a scaled-up version of the blade server concept. Old model - when you need extra computing power in the accounting system servers for end-of-month processes (the scenario commonly used to explain and sell the blade concept), pull some blades from a system with less load and add some to the accounting system. New model - when you need extra computing power in the data center, truck in a couple of containers of server racks and wire them in.

I also wonder whether there could be some DR/business continuity applications. A warm site could be just a big room with the storage infrastructure, the minimum number of servers needed to manage the data replication, and the necessary power and connectivity infrastructure, plus a contract with a vendor to deliver x containers containing y servers provisioned with z configuration within n hours to bring the warm site online to handle the production load.

Interesting stuff.