GeneWiki data comes from the GeneRIF database maintained by NCBI. In GeneNetwork, this is stored in GeneRIF_BASIC. [Authorised] Users of GN can add their own entries so that they are associated with a given symbol. In SQL, these edits are stored in GeneRIF.
Here's an example of a genewiki entry from GN1
Work related to this dump can found in: