This sounds interesting, Stateless Linux.
the goal: a uniform framework to cover all common ways of instantiating a centralized OS install read-only on multiple physical or virtual computers
This could be great for some of the server environments we have here at work. The IBM blade servers come to mind immediately for me, but I guess it doesn’t need to be just for that. Anyway, here’s the fedora-devel-list announcement, a proposal PDF document, a How To and some rpm packages.