Warning: This post has all kinds of unconfirmed rumors, but is indicative of where the future of high performance computing is going, at least according to IBM.
I had the pleasure of getting to see the Blue Gene installation at IBM's TJ Watson Research Center, which gives us a glimpse at the future of High Performance Computing (HPC). While IBM's webpage about Blue Gene is a bit out of date, it gives you a glimpse into what's running there. Installed in 2005, it has been upgraded a number of times since then with new HPC technology. Wikipedia has some more technical insight into the evolution of Blue Gene.
One of the things about Blue Gene is how much power it consumes, how much computing power is packed into a small space, and how it is cooled. The current Blue Gene models (the big black row boxes with a slant) make up the majority of the Blue Gene data center. This new "Blue Gene/P configuration" hosts 4096 processors per rack. The rack uses contained cooling with water-filled radiators cooling the hot air exhaust. The entire system fits in the alien-pod-shaped row container.