Akka certainly does. At the company I work for all our heavy lifting is done by an Akka cluster running on EC2.
We found that the difficulty didn't lay in getting Akka to work in a clustered fashion—that was simple—but rather in architecting our backend's work distribution mechanics so as not to overload any given node. I blogged about our experience with Akka: http://blog.goconspire.com/post/64130417462/akka-at-conspire...
In principle, transitioning from multithreaded to distributed with Akka is just a matter of configuration. I've never put this to the test, but akka does make this claim.
Do any of the library actor models offer something like that?