Just curious - apart from its ubiquitous use in specifying the presentation of HTML in modern web browsers, do any programs or standards utilize CSS?
Mozilla uses CSS to style the user interface of its products (Firefox, Thunderbird, Sunbird, etc.). It also uses CSS to bind logic to markup (-moz-binding).
Flex is also using custom CSS properties to style the interface.
Furthermore, the Qt GUI framework (written in C++) is using CSS.