The critical part of the RBAC implementation is the database design. Everything flows from there. (So take the time to study the design. Once you get it, everything else falls into place). Once your design is right you should be able to obtain all the infromation you need with just one query (and perhaps a little post processing to find out which privilege has priority over another.).

So there are really no secrets... all the information is on this page, which means you should be able to implement an RBAC system in any programming language. If you want to see how I did it in PHP send me an email. I would be interested to hear from people who want to port it to other languages.