Steve Vinoski of Iona says ...

As I noted nearly two years ago in this column, many distributed integration applications, including much of the software running the Web, are based on "middleware dark matter,"[2] which consists of dynamic languages like Python, Perl, and PHP. Not only is this phenomenon still true today but, based on the vast numbers of open-source projects revolving around these languages, it seems to still be rapidly growing. [IEEE Internet Computing: Dark Matter Revisited]

[2] The earlier column he refers to here is Middleware "dark matter".