As Ed Finkler points out there's a new article posted (written by him) on the C7Y site (from php|architect) talking about his Inspekt library - an introduction to the filtering library showing how to help make your applications safer.

Inspekt is a library for PHP4 and PHP5 that aims to make safe input handing easier, and unsafe actions more difficult. Inspekt establishes a new development approach by wrapping input within "cage" objects, and requiring the developer to use validation and filtering methods to test and manipulate the input data. This article provides a brief introduction to Inspekt and its capabilities.

The article covers all of the basics - what the library can do for you, how it integrates into your application and how it helps to protect you from potential problems with the data in your superglobals ($_GET, $_POST, $_REQUEST, etc).

Ed Finkler has released the latest version of his Inspekt input filtering/output validation library for PHP5:

I've uploaded the 0.3 release of Inspekt, the input filtering and validation library for PHP4 and 5. With this release, Inspekt completes the goals of the original specification for the OWASP SpoC007 project. I believe it is ready for "real-world" use.

Along with the new code being released there's also more documentation, API docs, a PEAR channel and a mailing list.