I'm very, very excited to announce that OWASP has chosen to fund development of what I'm calling "Inspekt" as part of their OWASP Spring of Code 2007. You can read my full proposal at the OWASP SoC Application Page.
The idea behind Inspekt is to provide a comprehensive input filtering and validation library for PHP. Building upon Chris Shiflett's original Zend_Filter_Input implementation
Some of the new features of this library include retrieval and filtering support for multidimensional arrays, a variety of helper methods to reduce code verbosity, compatibility with PHP4 and PHP5, and will be entirely self-contained (yet easily "pluggable").
Check out his full proposal for more details on what direction the project's heading and some sample code to show how it might all work.