Well, it looks like Akelos (http://www.akelos.org/) is taking the lead in the “Rails for PHP” race. It seems to have a better MVC architecture than cakePHP, especially where ActiveRecord is concerned.
MVC frameworks are an important design concept for modern Web 2.0 applications. I frequently consult on this topic and have a lot to say, too much to cover here I’m afraid.
The big difference between Rails and PHP is the dynamic nature of the Ruby language underlying Rails. So it’s really a Ruby vs. PHP discussion, not Rails vs. PHP. But you can’t talk about Akelos vs. Rails without talking about PHP vs. Ruby, so they tend to blend together.
I haven’t dipped that far into Akelos yet, so I’m sure I’ll be writing more about it as time passes.