"RoarVM, formerly known as the Renaissance Virtual Machine (RVM) is developed as part of a IBM Research project to investigate programming paradigms and languages for manycore systems of the future. Specifically, this VM is meant to support manycore systems with more than 1000 cores in the future.
It's compatible with Squeak 4.1 and Pharo 1.2 - follow the link for details. This is the fun part:
It is compatible with Squeak 4.1 and Pharo 1.2, has full closure support and was tested with 8 cores, 16 hyperthreads on Intel systems/tested with 56 cores on Tilera TILE64/TILEPro64 processors