Open source DRM solutions?

Feint writes: I'm working on an business platform for inter-company collaboration based on an open source software stack. As part of that platform I would like to integrate some sort of digital rights management for the documents managed in the system. The vast majority of articles are focused how good or evil it is to apply DRM to digital music or video. I haven't seen many articles address the open source solutions around how to protect business data like CAD/MSOffice/PDF/etc documents, which is a real need in business today. Can the Slashdot readership suggest some open source DRM offerings other than the Sun DReaM initiative (which hasn't had a release since Jan 2007)?