PHP has come a long way over the past decade and is still the most widely used web development language, with the biggest online community.
Two of the most significant reasons why PHP became so popular can be contributed to the ease of use and flexibility. The flexibility of PHP is a problem in its own, it opens a doorway for novice programmers to build poorly modeled software.

Experienced programmers know how fundamental good systems architecture is and always model their systems based on good Systems Design practices.
However, most of the time these programmers will implement architecture which they are comfortable with, and this specific architecture is not necessarily standardized, meaning other programmers might find it hard to understand the software.

MVC (Model View Controller) solves this phenomena, as its a standardized architecture and method for developing software. We've had MVC frameworks for some time now, to the likes of Zend Framework, CakePHP, CodeIgniter, Symfony etc.

Applying for a Web development position these days you'll find more than often that MVC and popular frameworks like Zend Framework, Symfony etc. to be a requirement.

I believe we're in a new era of web development, were many practices are standardized on a more global scale and The Zend Company / Zend Framework has definitely contributed to this, which has long been awaited!