The Bakery has five more great articles/tutorials they've posted recently covering topics like authentication and cross-controller input validation. Here's the list:

• Obvious trick to reduce amount of HABTM relationship tables - Trick howto reduce amount of HABTM tables in complex application
• Validation in another controller - You have 2 controllers, posts and comments, you want to be able to have a form on a posts view which submits to the comments controller, which does its thing then redirect to referrer - easy!
• ConditionalValidation behavior - The validations in cake 1.2 are great, but sometimes I needed to have conditional validation. Because the validations are set at model level, i did implement a behavior that allows to turn on or off validation.
• obAuth Simple Authentication - Authenticate your users and secure your controller actions from users belonging to certain groups. Or simply secure your controller actions to let any authenticated user to access it.
• obAuth Component Tutorial - This is a tutorial on how to use obAuth component: http://bakery.cakephp.org/articles/view/130

Check out The Bakery for more information on these and other great CakePHP-related articles, tutorials and commentary.