The Open Content encyclopaedia entry has now been published!
B. Haßler, T. Mays (2014). Open Content. An open chapter in the International Encyclopedia of Digital Communication and Society, edited by Professor Peng Hwa Ang and Professor Robin Mansell, Wiley-Blackwell. https://dx.doi.org/10.1002/9781118767771.wbiedcs154 (full article, pdf, comments invited).
Note: Also appears as Haßler and Mays (2015). (get link)
See also OCEE.