Steve pointed to SmartFrog this evening.  Here’s an example of what you might be able to do with it:

For example, a JBoss plugin would let you declare all the system requirements -memory options, system requirements, and the plugin would get the hypervisor to alloc the appropriate system, then we’d generate jboss boot scripts that would set up the JVM right, run the system, etc, etc. The cool thing is its dynamicity -you can deploy to new machines in a snap.

Sounds whacky cool.