I have been interested in an OS that would better implement virtualization and containers better, "closer to the hardware." I know most users aren't terribly interested in that sort of thing, but I think a lot of hacker-types would enjoy easily sorting projects into different areas. How nice would it be to easily spin up a couple different machines to test a server-client relationship on the same machine, without a handful of slow VMs?

I feel I don't know enough to see the issues with an approach like that, or know why it's not already mainstream.