Van Dale is the publisher of choice for the Dutch language. They contacted me last year through Kennisnet. Van Dale is interested in exploring what WiktionaryZ will mean to them. They are interested in collaboration and they are interested in business models of commercial organizations that collaborate with the Wikimedia foundation.
One of the great examples of such collaboration manifests itself in the books that are published in Germany by Zenadot Verlagsgesellschaft in Berlin. Together with the German chapter they produce books under the label WIKI press. If you read German I do recommend these books.