As part of the virtualization solutions I'm working on, I wanted something a little lighter weight than a full Qemu/KVM solution, which has a higer overhead than a kernel oriented container mechanism. There are many services that can be run with a common operating system. Containers provides the ability for solid segregation of services at the price of very low overhead.
For a container style of virtualization, I had been looking at OpenVZ (which is used by Parallel's Virtuozzo, I believe), Linux-VServer, and VirtualBox. However, on Debian's Upgrade Path to Wheezy, I see that Debian is deprecating OpenVZ and Linux-VServer.
Independently of this, I had earlier come across lxc Linux Containers. As such, it looks like LXC is the path forward for light weight, container-based virtualization.