When using command "/give @p minecraft:double_stone_slab", command returns error: "There is no such item with name minecraft:double_stone_slab".
In previous versions, you could give double_stone_slab blocks, but in current snapshot, it is impossible, preventing players from obtaining the smooth stone slabs (metadata 8), a block which many find to look better than the standard stone slab block.
This was not reported in any update notes.