Over on PHPEverywhere they have a link to a new presentation from Michael Radwin (at Yahoo) about One Year of PHP at Yahoo!.

This presentation (apparently shown at OSCON 2003), talks about how Yahoo as successfully used PHP to their advantage, making their systems faster and easier to maintain and scale. He also goes through some of the challenges that they found when using PHP, and some of the limiataions that are inherent to the language. They also mention using one of the many PHP accelerators out there to enhance the speed of your code that much more. Most of them are pretty simple to install, and can yield quite a difference for maybe 10 minutes of work.

It's an interesting speech, and is worth a look over. It's hard, though, to understand the finer points of these presentations without the audio that was with it...