I've actually been mulling over the possibility of combining the capability security model with a continuation-based web application framework, and think a Lisp

I've actually been mulling over the possibility of combining the capability security model with a continuation-based web application framework, and think a Lisp with continuations (like Scheme or Arc) might be the easiest substrate from which to start. It seems like a natural fit: your current capability grants would be closed over in any lexical scope, which means that a continuation would also encapsulate a capability set. Resuming the continuation would implicitly restore the security context active when it was captured.