Nether Bricks

Netherrack Bricks are an upcoming block in the 1.9 update. They may be another type of Netherrack

A brightened version of this image appears to show the possibility of a soul sand brick block too

Upcoming
Also, this small upgrade and maybe some other unseen additions could possibly mean that Notch will add the Sky Dimension as how he said that if the Sky Dimension is coming, the nether should be upgraded first.