I'm using Lisp to do vaguely AI-reminiscent stuff, though nothing as ambitious as early Lisp AI work was intended to be. In particular, Lisp is slowly working its way into the fit prediction algorithms at TrueJeans (http://truejeans.com/). I'm also doing some really basic algorithm prototyping for Credibli (http://credibli.com/) in Lisp.
I use SBCL and Clozure CL on OS X and Linux. Hacking with Slime, though thinking of trying Cusp, since just about everything else I do is in Eclipse these days.