I love OCaml, which this virtual machine says it is based upon, but doesn't it have issues with multi-core processors? That is, doesn't it suffer from a limitation due to its garbage collector?
[edit: ah, ok, to expand on what 45g said, ocaml is used to build the tools, but anything that targets the HLVM will end up using LLVM for runtime code generation - so it will either compile to assembly, or use a JIT VM. either way, any limitations in ocaml will only affect the tools, not the final compiled program]