If you haven’t yet heard of Docker, it’s quickly becoming the standard way of deploying applications in a Linux container, aka LXC. These containers are lightweight virtual machines, that offer increased density of running applications and a true ability to run applications anywhere (bare metal, VM, cloud, etc.). Boden Russell has written up some great benchmarking results of running applications and VMs deployed via Docker and KVM in an OpenStack environment. It’s amazing how efficiently Docker runs and the memory and CPU overhead are minimal compared to other hypervisors.
EDIT: Some highlights from the slide deck: Docker on average uses a fourth of the memory, can boot 1.5 times faster, and delete VMs up to 40x faster versus KVM.