Not that this is Lisp, but at our recent gathering I was babbling ineffectually about using the Join Calculus in Lisp. Join Calculus uses concurrency abstractions that can be (easily) embedded in a functional programming language. This is why I thought it would make a good fit for Lisp.
There are a number of papers; most centered around an ML-like implementation language, but the most accessible (to me at least) is "Modern Concurrency Abstractions for C". This paper describes a subset of the Join Calculus that extends C#, and includes many standard examples of synchronization and communication.
http://research.microsoft.com/~nick/polyphony/PolyphonyECOOP.A4.pdf