PHPSass is a PHP compiler for SASS, a popular CSS pre-processor language.
It is a fork of that has been under active development since August 2011.
It is up-to-date with the v3.1.1.5 specification of SASS, and is tracking v3.2 development actively.
We host the code on Github: github.com/richtheeek/phpsass
You can try the PHPSass parser online and compare it against the Ruby compiler here.
None yet, although there is an implementing Drupal module whose code covers everything that you need to know.
We *are* working on better documentation, and it will be on this website soon.