Hi!
After a number of difficulties and unexpected setbacks[1] I am happy to announce that geospatial search for Wikidata Query Service is now deployed and functional. You can now search for items within certain radius of a point and within a box defined by two points - more detailed instructions are in the User Manual[2]. See also query examples[3] such as "airports within 100km of Berlin": http://tinyurl.com/zxy8o64
There are still a couple of things to complete, namely sorting by distance (coming soon) and units support (maybe). Overall progress of the task is tracked by T133566[4].
[1] https://lists.wikimedia.org/pipermail/wikidata/2016-May/008674.html [2] https://www.mediawiki.org/wiki/Wikidata_query_service/User_Manual#Geospatial... [3] https://www.mediawiki.org/wiki/Wikibase/Indexing/SPARQL_Query_Examples#Airpo... [4] https://phabricator.wikimedia.org/T123565