Does anyone know the compatibility of the various Creative Commons licenses and the OpenContent license?
CC claims no compatible licenses: http://creativecommons.org/compatiblelicenses
However...
By my reading, OpenContent seems to be one-way compatible with the CC licences. It is more restrictive than the CC licenses, but quite similar to CC-BY-SA, but with the added clauses that you should "document changes" and "make a statement on warranty". As we are not making changes, and provide no warranty, I think it should be fine.
Also, I do not think that inclusion of these images constitutes relicensing, especially with an appropriate mention of the relevant license, and should be fine.
See SL copyright + the page forum.
Actually, inlining a picture (which was the initial question here) is sth. different than copying it.