Somewhat like Lua, if the working context was parametized into the functions then you could have multiple lisp eniviroments concurrently.
may not be a goal for this project... I'm just evaluating ulisp at the moment to see how it would work in a multitasking enviroment with indepedent scripts and maybe a message passing system (mailbox type thing). Then maybe a actor type model that can bridge to other scripts via message passing. That way a rogue script shouldn't kill the whole system.