Multiple Partitioned Kernels

[Young, Mike]

Ok, here's a weird one.  A friend has suggested that many moons ago, he used to configure Linux servers with multiple kernels at once, effectively hiding "virtualized" machines from each other.  This was back before the days of VMWare, Xen, and the like.  I'm having a hard time believing him, but hey - it's Linux - and most things are possible with it.  I haven't had a chance to discuss it in depth with him.

Has anyone heard of doing such a thing?

Cheers,
Mike.