Check out phpmac.com for information on running PHP on a Mac.
I’ve just started playing around with PHP a bit, since there’s a chance we’ll need to do something with it at work. Everything else we’re doing is ASP.NET, but we’re outsourucing something that’s liable to be done in PHP. As usual, I’ll probably end up supporting it after it’s delivered. I’ve got nothing against PHP, but it sure would be nice if I didn’t have to learn yet another scripting language!