Minecraft wiki entry for Redstone_Update, associated text: Realms
Scoreboard system
3 new commands: /testfor, /effect, and /scoreboard
3 new minecart variants: with hopper, TNT, and monster spawner
14 new blocks (excluding minecarts): nether quartz ore, activator rail, block of redstone, daylight sensor, dropper, hopper, redstone comparator, trapped chest, weighted pressure plate, block of quartz, and 4 variants of quartz.
2 new items: nether brick and nether quartz.
Block ID for sandstone double slab.