Information week has an interview with Microsoft President Bob Muglia. Which reveals Microsoft’s container is providing evaporative cooling in the containers.

InformationWeek: There's a next-generation container on the show floor?

Bob Muglia: In Chicago, we used the previous generation of container. The one on the show floor incorporates advances coming out of Microsoft Research. *~~Our servers have no fans in them.~~ Ambient air is drawn over a membrane onto which a small amount of water is released. I think it's two gallons an hour. The slow release of water drops the temperature of ambient air coming in through a system of louvers by 20 or 25 degrees and that's sufficient to keep the servers cool enough. You have to realize servers run comfortably at 95 degrees. Maybe you and I are not comfortable working at 95 degrees, but servers are.

*Note: this quote is struck out due to a reader pointing out the server fan noise. See this post for specifics.