Yes.
I've been looking for a UML tool to help me developing applications in PHP and I found Umbrello UML Modeller, witch is a free aplications for the KDE Desktop of Linux systems. You can dowload it at the following Web site http://uml.sourceforge.net/ or if you have a Linux distribution with KDE 3.2 it comes with it :-)
I got the 1.1.1 versions with witch I started to make the analisys and design of my actual project in PHP and apart for non having association classes al the other functionalities are ok.
This tool is also capble of reverse enginering PHP classes and creatre classes based on the class diagram you make.
So, it's a very good tool !
Serching Internet I also found another applications that does the same but his other one costs 800$ you can have alook at it at the following Web site http://www.microgold.com/
This other program runs in a Windows based system and to get acces to PHP funtionality you have to install PHP in a Windows machine ...
If you found new uml tools for PHP please tell me.
Bye
Hope that it helps you