Instant Data Center

What options does a company have if it needs to add or reconfigure capacity on short notice at a minimal cost? One option is a modular data center, a pre-configured collection of servers, storage, power and cooling equipment, that can be setup quickly with a lower overall investment than a custom-made data center. The catch - power capacity and telecom pipes may not be available - with that, a modular data center may still be a viable option.