Mid 90ies, I had the great luck to start a cooperation with Roman Maeder (now Director of HPC at Wolfram). In 1998, he developed the Parallel Computing Toolkit for Mathematica, the base of gridMathematica now on version 7 . It now extends Mathematica 7 wich has built-in parallelism. Its Leightweight Grid Manager, makes it easy to manage a networked pool of remote computation kernels.
But the core of Roman's tool is symbolic parallelism, making Mathematica's unprecedentedly clean-designed declarative language, a parallel declarative language. It enabled us to parallelize the machine learning framework and UnRisk in a few lines of code and to test parallelization approaches across scenarios for speed-up maximization.