On the PowerHomeBix.com site today, there's this new article from Comdev Software asking "Why PHP in the web applications?"
With the growing demand of PHP in the web applications, PHP modules have been introduced to cater for web design and web development needs in order to shorten the development process and eliminate writing PHP codes from scratch.
The article talks about the huge growth lately in the number of frameworks and "ready-made modules" that has happened lately. It mentions that these are growing because PHP's growing (and PHP's growing because...well, you get the idea). These modules can play an important part in an application and can cut down development time greatly - always good from a business standpoint.