As linked in WineTerroirist, a rather interesting article by FelicityCarter on the history of the revival of GemitscherSatz in Austria:
GS Revival

The article plays it as a phenomenon only around Vienna, but there are GS in Austria from much further afield. The IngridGroiss in the Weinvertiel is one such.
GS was originally a field blend of grapes co-fermented from an old vnyd. I wonder how many of these modern (since 2006) GS's are true to that model and how many are merely blends of separate varietal wines. Not sure how the Austrian law reads on this subject, but I'd be curious.