The UCN partners University of Cambridge and University of Nottingham have released the first open-source version of the Mirage operating system, available freely at openmirage.org. A complete article about Mirage 1.0 is published at the Mirage OS blog
There is also a Communications of the ACM article outlining the background of unikernels available online (read the complete article here).
Mirage is now being ported to the ARM architecture to support the hardware platform for UCN.