Erlang-style Concurrency For Other Languages

What libraries exist for other programming languages to provide an Erlang-style concurrency model (processes, mailboxes, pattern-matching receive, etc.)?

Note: I am specifically interested in things that are intended to be similar to Erlang, not just any threading or queueing library.

Message Passing Interface (MPI) (http://www-unix.mcs.anl.gov/mpi/) is a highly scalable and robust library for parallel programming, geared original towards C but now available in several flavors http://en.wikipedia.org/wiki/Message_Passing_Interface#Implementations. While the library doesn't introduce new syntax, it provides a communication protocol to orchestrate the sharing of data between routines which are parallelizable.

Traditionally, it is used in large cluster computing rather than on a single system for concurrency, although multi-core systems can certainly take advantage of this library.

Another interesting solution to the problem of parallel programming is OpenMP, which is an attempt to provide a portable extension on various platforms to provide hints to the compiler about what sections of code are easily parallelizable.

For example (http://en.wikipedia.org/wiki/OpenMP#Work-sharing_constructs):

#define N 100000
int main(int argc, char *argv[])
{
  int i, a[N];
  #pragma omp parallel for
  for (i=0;i<N;i++) 
     a[i]= 2*i;
  return 0;
}

There are advantages and disadvantages to both, of course, but the former has proven to be extremely successful in academia and other heavy scientific computing applications. YMMV.