I have never read the PHP License before. But I'm surprised to read in The PHP Licence version 3.01 (the latest) that you cannot use the name "PHP" in your product name. But There are many scripts that use "PHP" in their name like phpmyadmin, phpbb, phpnuke, cakephp and many others. Are they all illegal ? do they have a written permission from group@php.net?

May be I have misunderstood! here is the text as-is from the PHP Licence:
Products derived from this software may not be called "PHP", nor may "PHP" appear in their name, without prior written permission from group@php.net. You may indicate that your software works in conjunction with PHP by saying "Foo for PHP" instead of calling it "PHP Foo" or "phpfoo"

I cannot understand it. Either people do not respect the PHP Licence or the PHP License has other meaning that I can't get it.