UMCP is a hierarchical task network (HTN) planning system, implemented in Lisp as part of the Hierarchical Task Network Planning: Formalization, Analysis, and Implementation. UMCP is sound and complete HTN planner.
UMCP is still in its testing phase, but it is now publicly available. If you are interested in getting it, go to the manual page.
Please send e-mail to Reiko Tsuneto at firstname.lastname@example.org for comments and questions.