That all said, I prefer the modern world of general purpose operating systems with good commercial (Franz, LispWorks, etc.) and free (SBCL, Clozure, Clojure, etc.) Lisp development environments.
Smalltalk implementations are pretty similar in this respect, although both language families are still pretty fun. Erlang and Inferno/Limbo are both sort of guilty of this, but for slightly different reasons. But it's pretty inconvenient around the borders, getting into and ot of the "real" OS. It's sort of a mixed blessing that nowadays, most developer OSs are (on some level) Unix: there's a baseline, a set of facilities that can be expected to be present and to behave a certain way, so most modern Lisp-like languages are pretty friendly to the OS (or at least provide an FFI to C). The downside is that the baseline is POSIX, a little stiff sometimes and often quirky for historical reasons. (Still waiting for Plan 9 to catch on...Maybe I should stop holding my breath.)