Update 6 for Autodesk Revit® 2015 download: 64-Bit R2 UR6 Direct Download Link
EDIT Thanks to Cornel for this great link, it shows a page with various flavours of the updates for Revit 2015:http://revit.downloads.autodesk.com/download/2015RVT_RTM/UR6/AutodeskRevit2015UR6andA360C…