Well, they did release it as open source in a "Managed Runtime Initiative", but no one did anything with it and the site is now offline.
It's a set of patches to Linux, to cheaply implement the memory management tricks, e.g. batched operations on big pages without redundant TLB clearing, and a set of patches to the Hotspot JVM, which is where I think most people had trouble digesting it. See e.g. http://en.wikipedia.org/wiki/User:AzulPM/Managed_Runtime_Ini... for more details.
It ideally would have gotten enough traction that the Linux patches would get accepted in the mainline kernel. Ah well, perhaps someday.