Minecraft 1.4.6 is an update to Version 1.4.5 which adds a few new things...
New[]
Fireworks - Fireworks are now implemented officially! Fireworks come under two items - the actual firework and the firework star, an item allowing for the crafting of fireworks.
Netherbrick slab - A slab made of netherbrick.
Enchanted books - Books can now be enchanted! Enchanted books can be combined with other enchantable items in an anvil and that enchantment will be applied to the item!