I think it is important to highlight the implementation of hivemind allowing nodes to be run at a significantly reduced cost.  This is going to be a huge deal for developers and witnesses moving forward.  It will also help STEEM remain decentralized and remove some of the power from Steemit Inc. which I know some people have had an issue with.  It has actually been out and running for a while now, but https://steemit.com/@exyle did a good job of covering all of these things as they were implemented.