With this datasource you can easily add users to your Mailchimp newsletter. It works with CakePHP 2.x and is tested against the latest version(s) of it.
Please check the original blogpost on the original author's devblog for more background information.
It uses the current API version 2.0 from Mailchimp.
See Docs for details.
Possibly my Tools plugin for the admin backend (optional)