The Moonshot server is an interesting idea. The basics of it involve specialized servers built on a cartridge using low-power mobile processors. These cartridges share the usual common resources; power, cooling, fabric, switches, ILO, etc, which are all part of the chassis they are inserted into. The end result is that you can have 45 servers in one 4U rack space, using a fraction of the power. You can see it in the picture at the top of the post. Each of those individual cards is a different server.
The processors are Intel Atoms and each server has 8GB RAM and 1 SATA or SSD disk. The current focus is on web and cloud functionality, but the future calls for more server cartridges with different specialties, like memcache nodes as an example. For now, it is an interesting new direction worth keeping an eye on. There is a ton more information at the HP Moonshot website. And here is a shot of one of the Moonshot servers.