Outside of its security model, E is an interesting language to study because of its actor/object system. Objects live in 'vats', an actor with a local stack and an event loop thread/process. Objects can sequentially/locally communicate with each other in the same vat, but have to communicate as actors between vats.<p>AmbientTalk took it a few steps further, with a concept of near and far references, future pipelining, reflection etc.<p><i>edit: Oops, E already had near/far references and promises. AmbientTalk does add more on the reflection/meta-programming side of things and features for mobile ad-hoc networks such as object discovery.</i>