Previous versions of OS X came with apache and php4 installed. To enable it you had to edit /etc/httpd/httpd.conf
This has changed in Leopard so if you’ve upgraded you need to re-enable php. The location of the apache config file has changed and the installed php module is now php5. The apache configuration is now stored in /etc/apache2/httpd.conf.
So to enable php on Leopard, uncomment the line
LoadModule php5_module libexec/apache2/libphp5.soin /etc/apache2/httpd.conf and restart Web Sharing from the System Preferences panel. A by-product of the move from php 4 to 5 is that some of the default options have changed. So you may need to set some of the options to get your application to work. The php.ini file used by this php module is /etc/php.ini read more »
I've been using rails a lot lately and have been looking for a php framework that can give me a similar level of productivity. There are lots of php MVC frameworks. Here are some that seem to be directly inspired by rails.
After looking at each of them I've decided to go with Cake on my current project. It is simple and easy to use, works with php4 and is far ahead of the others in terms of documentation.