I don't remember seeing it advertised anyplace of the usual US retailers who carry R&K inks, but then I haven't really been buying ink much recently until this week.
Ruth Morrisson aka inkstainedruth
Despite my bluster that it would sell out as quickly as Aubergine - as of May there are still European supplies around. The good folks as fountainfeder, pennonia and appelboom have it (and ship worldwide), but my local stationer papierundstift has sold out.
I couldn't see any available at US stores (according to google anyway).