On the ThinkPHP blog there's a quick note about a study they've done on the relevance of business goals in the architecture of PHP applications.

PHP software developers and system integrators actually play an important role in running the world's largest web infrastructures. From Facebook, Gruner & Jahr, Kabel Deutschland and Lufthansa to a diversity of corporations, they all trust PHP and the respective systems built with it. It is not questionable that these systems provide a solid software architecture. The point of interest is how these architectures are aligned to the fast pace of changing business goals, which categories of business goals are considered during architecture creation and which means are utilised in projects.

The study (a 24-page study, in English) looks at some of the current strategies businesses are using in their application development, how to consider the right business goals and putting an emphasis on quality and capability of your organization. The study is free, but you'll need to register to get a copy emailed to you.