After rudimentary questions on the phone about why I want to work there, my background etc, they asked me to come in for a inperson interview.
You will be asked to sit in a board room and about 3-4 people will each have their turn to ask you questions. Expect ranging questions about Design Patterns, Testing paradigms (TDD, BDD), PHP, Zend Framework, Javascript, NoSQL solutions and other scaling technologies for the LAMP stack.
Questions will start easy, and will get harder to probe your abilities in each topic. I was very junior and still got the job, but i would imagine that higher positions and salaries will go to those who show expertise