In a new post to the blog at deasil.com, they talk about some of the lessons they see that can be learned from PHP and how it works/is packaged up.

PHP, though, came along with a breakthrough idea - mod_php was an everything in one install. Unlike mod_perl, mod_php gave you a programming language, templating language and extension all in one.

He advocates the PHP language developer's decisions to include everything into the core of the language which (while maybe not the best of decisions) has made PHP into one of the most practical development languages and has helped to make it one of the most popular and widely used languages on the web.