Dear all,
A relatively minimal system could permit the prototyping and exploration of such ideas without imposing too much esoteric baggage. It seems to me that L4Re, suitably enhanced, could provide such a foundation. It wouldn't be exciting for the security crowd (or wherever all the money is going this season) or make for good academic publications, but it might be useful nevertheless.
Sorry for playing Captain Obvious here, but there are other microkernel-based operating systems (both inside and outside the happy L4 family :)) that might be closer to achieving this goal of suitability for general-purpose computing.
A curated list can be found at http://www.microkernel.info/
Best regards
Martin Decky