It is for Web applications. Writing a website using Delphi for PHP is really easy. It gives a feeling of writing a desktop application because everything is based on events, like Delphi. Even for Ajax actions only supplying a handler for the appropriate event of the web element does all the task.
Howere, projects written in Delphi for PHP have lot of files and dependencies that is normal for a RAD tool. Because of that, I prefer to write plain PHP, and my favorite IDE is
NuSphere PhpEd.
NetBeans has support for PHP too. I didn't check it out yet but it should be as good as Java in NetBeans.