Please note that they are currently live on desktop (Windows, OSX), but it will take an extra week or two for them to ship on mobile (iOS, Android) and console (Xbox One) platforms. If you try to use these materials on those platforms right now they will look and shape like grass. So if you’re planning to update your games to use these, check that they have been released on the platforms your game supports first.
EDIT: They are now live across the board (on all mobile/desktop/console platforms)
The types are all there but the simulation is disabled because we’re waiting for other platforms to get them. If we don’t then the moment somebody joins the game from mobile bad things start to happen to the simulation.