They had a working version to test on? Surely such a mythical beast doesn't exist?
There's also Arch Hurd: https://en.wikipedia.org/wiki/Arch_Hurd
Personally I want Hurd and Minix 3 to gain support, as I feel that micro-kernels are the way to improve operating system security.
The only successfully commercial attempts so far have been Symbian and QNX.