PHP Development Environments?

rbolkey queries: "I've been looking for a comparison between Zend's PHP IDE, NuSphere's PHPEd, and Maguma's PHP4EE, but have failed to find any. Does anyone know how these IDEs compare? Are they useful? Are they worth the price?" We last handled this question over a year ago. PHP has changed since then, and I'm sure more development tools for PHP have been released since then. What recommendations do you have for PHP coding environments? What features do you find the most useful?