There has been lots of promotion of the data center in a container concept. Sun was one of the early proponents, and Rackable recently showcased their version at the LinuxWorld Expo.
I believe there is some significance to these configurations behind the basic promotional aspects. By putting a fixed amount of computing resources in a 8x8x40 box, it is very easy to concretely identify the space, power, and cooling requirements. Once you are within a building, it is often much more difficult to isolate those variables.
So even if a company does not buy the "container concept" I bet they are paying close attention to the environmental ratings of the configuration at that scale. Most customers do not buy just one server, or even one rack of servers...they buy multiple racks. The data center in a container concept makes the environmental ratings meaningful at a unit of measure suitable to large data centers.
Following is a super short video tour of Rackable's data center container at the LinuxWorld Expo. Enjoy.