CakePHP-JQuery-Helper is a project mainly written in ..., it's free.
A drop-in replacement for Cake's existing Prototype helper
I pulled this down from LoadSys' website and put it on GitHub. It's under the MIT License and copyrighted by them, as explained in the header. For more information go here: http://blog.loadsys.com/2009/05/01/cakephp-jquery-ajax-helper-easy-scriptaculous-replacement/