Credo's aim is to create a better infrastructure for user management on Unix systems. Currently, things like PAM and NSS allow for flexibility, but not for ease of configuration. Most importantly, they work different on each flavor of Unix, which can be a large hassle. The idea is to simplify this with a single, centrally administrated configuration file.
On the technical side, the idea is to have a central daemon that connects to the configured user management services. It is integrated into the system through various hooks, e.g. NSS and PAM modules. Only these modules must be ported to each Unix flavor. Long-term plans also include a network service to handle simultaneous password changing across several systems.
Credo is still in the early development stages, there is no usable release yet. Development happens in a private Subversion repository, which is exported to the SourceForge-hosted public CVS in irregular intervals. If you're adventurous, you can download the current source via CVS and play with it. The source code contains Doxygen inline documentation.
This project is hosted by SourceForge. You can use the trackers to submit bug reports, feature requests, and patches. Other resources are listed on the project summary page.