I don't see an official announcement here, so in case you missed it:
Multi-process Firefox, aka Electrolysis, is now being pushed on FF Developer Edition (alpha) 40 builds. The clock for the NSS/NSA merge is ticking.
https://bugzilla.mozilla.org/show_bug.cgi?id=1058542
Electrolysis is coming, hide yo kids hide yo script
Electrolysis is coming, hide yo kids hide yo script
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:40.0) Gecko/20100101 Firefox/40.0