There's a lot of activity going on in this space right now, which is great. I was working on my own project very similar to this one, which I called 'fleet':

http://www.github.com/marssaxman/fleet/

I've recently decided to stop working on this and to start contributing to IncludeOS instead, since they have a lot of energy and good ideas, and they're getting farther than I was on my own:

http://www.github.com/hioa-cs/IncludeOS/

One great thing about unikernels is that fragmentation is not really a problem: it's a good thing to have a healthy, diverse ecosystem of unikernel libraries adapted for different purposes.