From George Schlossnagle's Weblog:

Looking over this excellent slide presentation from here, the architecture of a former large employeer, as well as the architectures of some clients of mine who shall remain nameless less they fire me for blogging.

What this convergence suggest to me is that PHP is starting to develop a large architecture standard deployment pattern. [...] While one should be leary about pretenders to the best practice's throne, I've watched these ideas and patterns develop independently over a number of years, and I think this is the real thing.

So what does a best practice buy you? While it's not a silver bullet for performance, scalability or success, it does give you a solid footing on which to build an architecture. What this means is your design anticipates common problems (high volumes of traffic, high query loads) and keeps you from shooting yourself in the foot. There's also significant advantage in building an architecture that looks like other large architectures, as products can tailor themselves to run efficiently in that setup.

A move in this direction (as he mentions) is a very good thing. Moving towards the more quality code/applications can only mean good things for the PHP world...