Daniel Weinreb has quite a comprehensive survey of active Common Lisp implementations. By his criteria there are 10: ACL, ABCL, CMUCL, Clozure CL, CLISP, Corman Lisp, ECL, LispWorks, Scieneer CL and SBCL (MCL's “level of maintenance” disqualified it). [via Xach.]
Posted by jjwiseman at December 11, 2007 06:29 PM