The company this week unveiled what it is calling its "Generation 4 Modular Data Center" plan, a blueprint that will define its cloud data-center infrastructure in the next five years.

The data centers have four walls and a sophisticated perimeter security system, but are open to the elements as they lack a roof. Trucks wheel the boxes into the enclosure where they are connected to power/cooling stations before being brought online.

It's a bold plan to drive industry thinking about how to construct and operate data centers in a world of capacity spikes, real-time needs for computing power and expanding green initiatives.

"We believe it is one of the most revolutionary changes to happen to data centers in the last 30 years," said Michael Manos, general manager of global foundation services for Microsoft, in his blog introducing Microsoft's Generation 4 plan.

BusinessWeek reported last month that Microsoft said it was going to "reinvent the infrastructure of our industry" by building some 20 data centers that can carry a price tag as much as US$1 billion apiece.