Recent significant open font releases: Fira Sans, Fira Mono and Source Serif Pro
Don't miss the newest version of Fira [Sans|Mono] (3.1 or 3.106 currently)
commissioned by Mozilla from the Spiekermann
foundries. It should soon appear on http://github.com/mozilla/Fira
And check out Adobe's Source Serif Pro
now also available on https://github.com/adobe/source-serif-pro
There are lots of interesting questions ahead in terms of how best practises will be defined and applied to open format workflows with multiple tools, DVCS tree structures and ongoing maintainership and release engineering of open fonts such as these...