> Doesn't seem practical. It might be useful as a learning-framework for MPI / Supercomputer programming... but it wouldn't be a tool that I'd use personally.

I read somewhere that some real supercomputer systems programmers actually use toy clusters of Raspberry Pi's to test their scheduling software. It helps speed up their development cycle because they can do initial testing on their desktops.

Edit: I think this is what I was thinking of: https://www.youtube.com/watch?v=78H-4KqVvrg

http://www.bitscope.com/blog/FM/?p=GF13L