I've switched the Oxford Guide licence to Attribution-ShareAlike 2.5 http://creativecommons.org/licenses/by-sa/2.5/, http://lists.ibiblio.org/pipermail/cc-licenses/2005-May/002313.html from 2.0.
This essentially only formalizes the ability to attribute to a collective work (ie the wiki) as was already detailed in the licence policy, so this shouldn't affect anyone's rights in any way.
Cheers,