Slush has posted an official page for the stratum protocol now, including new extensions.

http://stratumprotocol.org/

http://stratumprotocol.org/stratum-extensions

Of note, the most important extension added is: mining.configure which supports “version-rolling”

The executive summary is that version-rolling means poolside support for asicboost. Asicboost is now under the defensive patent license meaning anyone can add it to their hardware provided they sign the DPL.