We started the process of upstreaming our multicore OCaml branch to mainline OCaml, and so I started posting regular updates to the community forum.
The most common question we get is how to contribute to the overall multicore effort. As I noted last year, we are now in the process of steadily upstreaming our efforts to mainline OCaml. Therefore, the best way by far to contribute is to test for regressions or opportunities for improvements in the patches that are outstanding in the main OCaml repository. -- me, on the discussion forum