jan 27, 2009 - Cubase Variaudio
This was designed to pitch correct vocals and instruments, much like the Antares Autotune. Cubase Variaudio was created by Steinberg, I am not entirely sure when they introduced this however I do know that you can find this on Cubase's Software as early as Cubase 5 which was released January 27th 2009.
Added to timeline:
Unit 5 Music Technology in Context