Nu is an interpreted object-oriented language.
Its syntax comes from Lisp, but Nu is semantically closer to Ruby than Lisp.
Nu is written in Objective-C and is designed to take full advantange of the Objective-C runtime and the many mature class libraries written in Objective-C.
Nu code can fully interoperate with code written in Objective-C; messages can be sent to and from objects with no concern for whether those messages are implemented in Objective-C or Nu.
Although you can compile Objective-C on lots of platforms, right now Nu is only available for Apple systems running Mac OS 10.4 or later.