Padraic Brady has noted that the latest release candidate of the HTMLPurifier software has been posted for download:
HTMLPurifer is possibly the most understated underpublicised quality library in PHP today. I consider it a fundamental standard library that is automatically included in every PHP web application I start these days.
This latest release candidate (their first!) includes updates on two major features - the use of autoloading and a change to the way you use the filters. Check out a demo of it in action or just download this latest release and try it out for yourself.