Jentu is disk block “streaming” where you take the hard drive out of a computer, do a PXE boot, and it connects to a central image which is run locally on the desktop. You get bare metal (i.e. no hypervisor) performance on your desktop, and with 100MB or 1GB networks and a bunch of drives and cache in your server, you can actually get better performance than a local disk.
The real advantage though is the central management, security, and the ease of reverting back to a stable state (or swapping out an image) just by rebooting the desktop. (It’s like an instant version of Ghost, or a more secure version of Deep Freeze.)