I found a link to Michael J Radwin’s PHPcon presentation about Yahoo’s move from a proprietary page scripting language to Yahoo in Anil’s list of links. This is the first really in depth behind the scenes look at how things work behind the scenes at Yahoo. I always wonder how things work at the really, really big Web sites, so the presentation is quite a treat.
Also interesting are the reasons why they chose PHP over various other languages. They rejected Perl in part for the reasons why I don’t use it as much any more, and they rejected Java/JSP for the simple reason that the threads implementation on FreeBSD is poor.