Noritsuna Imamura showed an ARM cloud cluster built with 6 Pandaboards at Linaro Connect Q4.11. Noritsuna is a member of the Open Embedded Software Foundation (OESF), a Japanese organization that support Open Source embedded software.
The cluster is made of 6 panda boards with a total 6 GB of RAM (1GB per board) that runs the Google App Engine (http://code.google.com/appengine/) in Ubuntu/Linaro 11.09 release. The middleware used is TyphoonAE, a full-featured and productive serving environment to run Google App Engine (Python) applications. This type of server hosts web applications such as Rietveld (used in the demo below) to be run on (thin) clients. There are also plenty of other software (required by Google App Engine) that runs in this ARM cloud such as MySQL, Apache2, memcached and more.
In the video, a power meter shows that the cluster consumes about 35 W in low activity mode.
Norisuna had a comparison table that showed the Pandaboard cloud (OMAP4 @ 1GHz – 12 Cores) uses 4x times space and 5x less power (50W vs. 257 W) than a Xeon 1.8GHz Quad Core server with about the same amount of processing power and memory (6GB vs. 8GB).
One drawback is that the software is located on the SD Cards of the pandaboards so it can be relatively slow, but this could probably be replaced by SSDs connected via USB without affecting power consumption too much.
The presentation slides are available at http://www.slideshare.net/noritsuna/panda-cloud