I think that generally depends on the field. For example, in the Microsoft world, everyone cares about Microsoft certifications.

As for the PHP world, if you are a freelancer then I would definately recommend taking the Zend exam if you can - it will help seperate you from the thousands of other freelance PHP developers out there and shows potential clients that you actually have some willingness to learn and the drive to progress. It also shows that you are not afraid of a challange which is what I look for in developers

I can honestly say that if I was hiring a PHP developer, and had two candidates, both of equal calliber, I would hire the one with the Zend Certification.

Alan