A new level of compartmentalization is appearing in the form of embeddable language run-times.
[Kernel] [Xen/KVM] [Docker] [embedded language runtimes]
Running sandboxed, user-provided scripts becomes more desirable as the features of Internet services/websites increase in complexity.
The neur0n project is a reimagining of this setup with the management of multi-language-VMs as the core. There is a small about of C++ to listen to a pub/sub channel (in this case, redis, but nanomsg in on the roadmap), where commands are received to launch a language VM and load it with the script contents of a URL. The first supported VM is mruby - the embeddable subset of the Ruby language.