Converted undo/restore interface to use OOUI. You can test it here (phab:T134643).
Fixed an other rounding issue on geo coordinates (phab:T158772).
Added thumbnail images to the Wikimedia Commons suggester (phab:T160319).
Continued working on introducing Lexeme entity type.
Finishing federation prototype.
We are going to change all snak, reference, and qualifier hashes with the planned DataModel 7.0 release. If you are a tool developer, make sure you do not persist hashes, and never use them to request edits to entities. Statement IDs are safe (phab:T157965).
There's now also a #100wikidays challenge on Wikidata, aptly named #100wikidatadays! It is a personal challenge in which a person very significantly improves (at least) one Wikidata items per day, for 100 days in a row. There was already a version of the challenge on various Wikipedias, on Commons and on Wikisource - now on Wikidata as well. Participate and make Wikidata shine!