The Witcher website has word that
The Witcher: Enhanced Edition will be available on September 16 in North America and September 19 for the rest of the world. Thanks:
Blues. The Witcher: Enhanced Edition includes two new mods, The Price of Neutrality and Side Effects, a mod editor allowing you to create new adventures, lots of graphic and gameplay features (100 new gesture animations in dialogue and cut-scenes, giving conversations with NPCs a more natural feel, improved inventory, auto-save option, auto-looting of containers and a character differentiation mechanism), as well as lots of bug fixes and improvements starting with load times shortened by 80% and ending with a correction of all the English dialogue and voice-work.