Let's Play 'Name That Data Center'

I can't resist a blog post titled "Secret Data Center?" Professional photographer Gregg Reiss has posted photos from inside a major data center operated by one of his clients, a company that Reiss says "most likely created the Internet Data Center." He writes:

In posting the shots on the "secret" facility on the Internet, Glenn seems confident that folks won't be able to identify his client from the photos.

Is he right? Let's find out. If you can identify this facility, or think you know who the owner is, share in our comments. Some potentially useful background information: Reiss is based in Kansas City, and his company's client list includes Sprint, IBM and DST Systems (it couldn't be that easy, could it?). And the data center operator has "zillions of servers."

UPDATE: The data center in question belongs to 1&1 Internet, as noted by Chris in the comments. Thanks for all who ventured a guess!