Marc talked about the differences between MongoDB and neo4j, two NoSQL offerings which can easily be used in a Java or JVM-based application, but also many other languages.
Helmuth made a short presentation on App Engine Endpoints using Python. And the last talk was about Firebase, a JSON-based NoSQL cloud storage with offline capabilities, many client libraries, and realtime sync.
The next event is Google I/O Extended 2015 - 28 May 2015, 17:30 @Stockwerk. See you soon!