Way cool: Objective CLIPS is a new development environment for OS X. From the description:
Using Objective C runtime introspection, CLIPS, and FScript, it is possible to write intelligent Cocoa applications. Any Objective C object can be asserted as a fact in CLIPS, however, CoreData provides an additional meta model along with object persistence.
CLIPS is an expert system environment that is based on a Lisp dialect and enables the management of rules and facts, as well as reasoning about them. FScript is a scripting language inspired by Smalltalk that works directly with the ObjectiveC classes in OS X. Both together should enable pretty cool things, especially since databases and documents can also be easily created with CoreData. And both languages (CLIPS and FScript) I found quite interesting in my experiments with them - CLIPS was even used by me for a longer time as a "Lisp replacement", because it is indeed a rather old-fashioned Lisp, but is equipped with powerful additional abstraction possibilities.