PHP Structured Text is my answer to wanting a Zope-style structured text implementation for PHP. It's not exactly the same syntax as Zope's, but borrows some ideas from it, mixed with a couple of my own. My thoughts when I was first defining and implementing it can be found here and here.

While it may not suit your particular needs, it's met mine fairly well, for the last year-or-so, on a couple of projects. If not, feel free to alter the code to better fit your needs.