It's back up now; the ML TCP stack was running a pcap dumper for debugging, which didn't cope well with a hackernews link.

Hacking is going pretty well on Mirage. The longer-term plan is to generalise the support libraries to work with other languages (particularly HalVM and GuestVM for Java), but it's far simpler to work with just OCaml for getting the first cut out. The Xen Cloud toolstack (also written in OCaml) is currently being adapted to support low-latency microkernel establishment, which will remove much of the hassle of coordinating multiple Mirage 'processes'.

Another interesting performance-related aspect has been the heavy IPC workloads that result from using many VM-VM interconnects. Some early benchmarks in http://anil.recoil.org/papers/2012-resolve-fable.pdf .

The (inadequately developed) point was that this idea could be built into an entirely new operating system with e.g. a different notion of a process—as opposed to building new tools on top of Unix—and that this "operating system" could be a lightweight layer like HaLVM or Mirage, so such ideas could be explored without committing to building an entire OS.