Daniel @ RethinkDB here. We'll release the details shortly. This was running on 12 core Xeon servers with 2 SSDs each in software RAID 0. There were also additional read queries running at the same time as the write queries, and the read throughput that coffeemug posted is the sustainable increase in reads/s that you get when adding an additional server to a cluster. Single-server performance is much higher due to missing network / message encoding overhead.

I realize these numbers alone are still not very meaningful and there are many remaining questions (size and structure of the data set, exact queries performed etc). Rest assured that all of these details will be mentioned in the actual performance report that should be up soon.