On WebProNews.com a PHP roadmap has been posted - a comprehensive look at what PHP is and how it's evolved.
We expect our readers to have a more than firm handle on what PHP is, but for completeness-sake: PHP (a recursive acronym of PHP: Hypertext Pre-processor) is an open source, server-side web-scripting language for creating dynamic pages.
They look first at what PHP has to offer, then how it's evolved, and finally a comparison of PHP to several other langauges, including Perl, Java, and Cold Fusion.