Mica:

Mica is a system for building network-accessible multiuser portable applications. It is a programming language and object environment designed to be accessible by more than one programmer at a time. It includes an implementation of a mostly pure object oriented language. Automatic persistence, reflection, strong encapsulation, multiple dispatch, and run-time security are some of its features.

Which reminds me that one of the unusually smart things about LambdaMOO was its security model, in a world where "untrusted code" was everywhere. Individual verbs (methods) execute with the privileges of their author, as I remember. Which is neat (if your world includes wizards to do the dirty work)...