[nivla]

Same here. I was surprised to see it not even being listed despite OP's original data source having it.

http://www.freebase.com/view/computer/programming_language

[yaph]

PHP is a small node, according to the data source it has influenced only 2 languages.

The fact that PHP is widely used doesn't make it influential on other languages, in the case of PHP the opposite may be true.

To find PHP in this random layout restrict the paradigm to "Interpreted language" and move your mouse over Python, the PHP label will show up.