Are you folks familiar with the SBUML project?
It doesn't appear on the "Related links" page at
<http://user-mode-linux.sourceforge.net/links.html>, but it looks like
an interesting project -- they've added code to UML to allow
"snapshotting" of the virtual machine state, so you can create an image
of a running system that will "boot" back up exactly where it left off.
They have some really interesting ideas, and it looks as if development
on this project was active as recently as July.
I found this project via a published paper here (long URL, so apologies
of it wraps):