Although PHP has now grown to become the number one development platform on the web, there is no abundance of certification and training courses as is available for other languages. ASP is backed by Microsofts training program, but also enjoys a lot of third party training support. The likelyhood is that, as there is no central commerical authority behind PHP, only a few established training programs exist.
The most popular and most sought after certification in PHP is provided by its creator, Zend. The certification, Zend Certified Engineer, consists of an exam of fifty to seventy multiple choice questions, which have to be answered within a two hour period. The exam can be done online and you can start by buying a $125 exam voucher from the Zend website.
What are the benefits of achieveing Zend Certification? The primary goal would be for recognition, which is very helpful as a developer. Second, your name will go into a directory of Zend certified engineers and your name will come up for searches done on your locale. There are many more benefits, but if you are looking at PHP development as a long term career path then it is essential that you get certified.