I work on the team that built this and many of our other ranking tech. I can answer any questions people have.
Also shameless plug: using this tech we released some artificial search sessions as an exploratory dataset. <a href="https://github.com/dfcf93/MSMARCO/tree/master/ConversationlSearch" rel="nofollow">https://github.com/dfcf93/MSMARCO/tree/master/ConversationlS...</a>
Good press release title. Now just add it to the pile ;) <a href="https://github.com/erikbern/ann-benchmarks" rel="nofollow">https://github.com/erikbern/ann-benchmarks</a>