Both David Mazières of SDF and Bob Glickstein of Interstellar released articles distilling the Stellar Consensus Protocol.
MobileCoin contributed the "aCounter" optimization to an updated draft of the Stellar Consensus Protocol white paper.
Stellarbeat has added a quorum monitor/explorer. “The quorum monitor gives more insight into the quorum set connections of the Stellar network, active nodes, failing validators, clusters. It also allows you to toggle nodes on/off and see the effects on the network.”