From the [[ https://www.wikidata.org/wiki/Wikidata:Development_plan#Automated_list_generation | development plan ]]:
Users are able to write queries like “all poets who lived in 1982” or “all cities with more than 1 Million inhabitants”. They are entered in a page in the Query namespace and internally saved as JSON. They are then executed when resources are available - usually not immediately. The result is cached. A query can be set to rerun at regular intervals or on-demand by an administrator. The result of the query is shown on the same page. It can also be accessed via the API. The clients can include the result of a query in their pages to for example create list articles. This will enable for example to have automatically updated list articles on Wikipedia.
However it is not decided yet whether the Queries will reside on Wikidata.org or on wiki. It's part of the discussion we will have to define the needs better.