I have been playing with PHP lately just to learn more about it. I can assure you that I am more dangerous than anything else with it. My web development framework of choice is the ASP.NET MVC Framework.
I will say, however, that my tinkering with PHP has led me to several MVC Frameworks based on PHP, like Zend, CodeIgniter, CakePHP, etc. It has been an eye opening experience to use other implementations of MVC other than the two I know quite well ( Rails and the ASP.NET MVC Framework ).
What I also like about these frameworks is that they can easily be developed on a Mac, which I also love as a development machine. It's not that I have a fondness for OS X over Windows 7. What I love is that I can run both operating systems on a Mac and quite easily develop in the framework / technology of my choice, whether it be Rails, PHP, ASP.NET MVC Framework, Webforms, etc. I can either run both OS's simultaneoulsy using VMware Fusion or Parallels or boot into a particular OS of my choice.
What also excites me about doing PHP Development on the Mac is that I finally get to use Espresso for PHP Development. You can certainly use TextMate, JetBrains Web IDE, etc. but I have always been wanting to use Espresso, which I purchased some time ago. I am not using Espresso to build professional PHP Web Applications, so I can't really comment on the pros and cons of its features ( other than the lack of built-in support for source control ), but what I do love about it is the clean and easy to navigate user interface.
Shown below is a snapshot of Espresso 1.1.1 while playing with the scaffolding features of the CodeIgniter PHP MVC Framework.
I don't plan to jump into the features of Espresso as you can easily get a tour on the MacRabbit website.
If Espresso is not quite your thing, I recommend checking out the new JetBrains Web IDE built specifically for PHP Development. JetBrains makes some really nice development tools. I use ReSharper, TeamCity, and RubyMine with great fondness. JetBrains Web IDE comes in flavors for Windows, Linux, and OS X. I have installed the beta of JetBrains Web IDE and plan to look at it in more detail myself.
Although I will stick with the ASP.NET MVC Framework for professional development, I do love to play with other development environments and frameworks like Rails, PHP, and who knows what is next. If you are interested in PHP Development on the Mac, I would certainly look into Espresso, TextMate, Coda and the JetBrains Web IDE for development.
Hope this helps.
David Hayden