Amber noticed this on her Twitter feed: a L4 microkernel based para-virtualisation that runs on the A9: http://l4dev.org/
They're currently running the 11.12 LEB on a Versatile Express. The project overview: http://l4dev.org/codezero_overview
talks about their 'hyperswitch' method to reduce the para-virtualisation overhead and reduce the number of changes to the Linux kernel.
-- Michael