Multi-machine tool in the spirit of moreutils' `parallel`?

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http://unix.stackexchange.com – parallel from moreutils is a great tool for, among other things, distributing m independent tasks evenly over n CPUs. Does anybody know of a tool that accomplishes the same thing for multiple machines? Such a tool of course wouldn't have to know about the concept of multiple machines or networking or anyhting like that -- I'm just talking about distributing m tasks into N clusters, where in cluster i N_i tasks are run in parallel. Today I use my own BASH scripts to accomplish the same thing, but a more streamlined and clean tool would be great. Does anyobdy know of any? (HowTos)