The seL4 microkernel
seL4 is "The world's first operating-system kernel with an end-to-end proof of implementation correctness and security enforcement" originally developed (as far as I know) at UNSW, further developed at NICTA.<p>The original project home page is at <a href="http://ssrg.nicta.com.au/projects/seL4/" rel="nofollow">http://ssrg.nicta.com.au/projects/seL4/</a> and the new page is at <a href="http://sel4.systems/" rel="nofollow">http://sel4.systems/</a><p>Downloads at <a href="http://ssrg.nicta.com.au/software/TS/seL4/" rel="nofollow">http://ssrg.nicta.com.au/software/TS/seL4/</a>