Linus has accepted a patch which allows 64-bit CPUs to virtualise processes. It can also, apparently, be built as a kernel module.
The virtual machines are simple user-space processes, and (as with Xen) the peripheral interfacing is handled by a modified QEMU driver, making virtualisation relatively simple & easy.
This is going to make testing things much simpler, from my article-author’s perspective. Rather than have a handful of machines around to test each implementation on, I can run them all from one.