On Wed, Jun 19, 2013 at 11:15 AM, Denny Vrandečić <denny.vrandecic@wikimedia.de> wrote:
I agree that the different projects have different requirements. But I think we should strive for a small number of "Wikidatas" - you could have made the same argument for Commons, after all.

The two projects that might need it most are Wikivoyage (hotel/restaurant listings) and Wikiquote (semantic quotes), though in the end they could be included in Wikidata with different entity types.
Wikisource is aligned with the existence of source items in Wikidata, so other than having a "S" namespace for sources (or not) and adapting the extension to work in Wikisource, there is not much need of development from the Wikidata side. See more here:
Right now, I think there is a need for Commons to have better support for data - we are working on a proposal text for that - and Wiktionary - as it is really a different system - needs some special treatments - we have just send a proposal text for that.

The Wiktionary proposal is a great start. I'm excited about the Commons proposal. It would be fabulous to have an "F" entity type for files :)

(You can always go further and say "but it would be better if we supported Wikibooks with structured data about the books and its chapters" etc., but at some point you need to weigh implementation effort and cost and the expected benefit)

Wikibooks (user-generated text-books) is a special case, a bit different from Wikisource (digital versions of existing sources).
However both can be treated in a similar way. I agree that the potential benefit of linking chapters wouldn't be that high.