Disclaimer: I am working for a shop with much PHP knowledge. There are some really nice frameworks for PHP - for example we are using Yii (http://www.yiiframework.com/), Symfony (http://www.symfony-project.org/) and Flow3 (http://flow3.typo3.org/). I was using Yii in one of my projects and it worked really nice (altough I can't compare it to Rails or Django, because I have no experience with those).