There is a Lisp IDE available with Clozure Common Lisp (née OpenMCL). It looks fine, although I like SLIME better. Clozure, however, is the bees knees: an order of magnitude faster compilation and execution on a 64 bit Intel Mac, and a better "user experience" in general. Look around on common-lisp.net for Rittweiler's new slides on using SLIME, they're very helpful.
