Where do the various pieces fit in the ecosystem?landscape?
The OSS IDM project attempts to package an overall stack to make implementing individual pieces.
The OpenRegistry project is designed to help individual institutions to gather their institutional identities together.
The LDAPPC-NG project addresses provisioning.
OpenLDAP is a mature LDAP implementation.
Grouper is a mature group management tool.
Shibboleth enables federated access management.
Domesticated applications easily integrate with your infrastructure, like a CASified application. In a perfect world, apps are easily made domesticated and therefore they will.