Just finished a co-authored piece with Christine Wihak on using PLAR (Prior Learning Assessment and Recognition) in the open education space.
It turns out that some of the more popular ideas and practices in open, personalized learning, such as badges, personal learning environments and/or the use of OER for self-study, are actually least compatible with PLAR assessment. On the other hand, emerging open course models and established standardized testing procedures actually present far greater possibilities for credentialing through PLAR.
This paper (available as a .pdf) uses a version of the diagram (right) to illustrate how three different options for the translation of open educational experiences into postsecondary credentials might work.