Well, for starters, the new update, I can't decide on weather its a good thing that adventure mode in only for LAN... Or if its a really annoying thing, because my dad wants to play adventure mode, and use it for his computer class... So basically, the new update includes, NPC Trading, LAN Servers (LAN: Local Area Network), Emeralds, Temples, Large Biomes, Single Player "Cheats", And many more. I really just listed the main stuf, other things I may be forgetting are probably not really that "Important" to me, depending on how my brain didn't memorize it. ^.^ Anyways, if you want the update in Notch's words, I'll list it below.

+ Single-player now runs a server internally
+ Publish the single-player instance to LAN
+ Automatically detect LAN worlds in multi-player screen
+ Added o cheatso option in single-player (enables commands)
+ Added o bonus chesto option to give players a quicker start in a new world
+ Added adventure mode (work in progress)
+ Added trading with villagers
+ Added emeralds, emerald blocks and emerald ore
+ Added cocoa beans to jungles
+ Added the Ender Chest
+ Added tripwires
+ Added new creative mode inventory with search functionality
+ Made it possible to gain enchantment orbs from mining ore and smelting
+ Added writeable books
+ Added o large biomeso world type
+ Added temples to jungles and deserts
+ Added chat settings
+ Added option to turn off and view snooper data
+ Added more information on the debug screen (F3)
+ New launcher with o Play Demoo button if not premium user
+ Added /seed command to see map seed
+ Added /defaultgamemode to set default game mode in a world (affects new players)
+ Added /debug command for profiling
+ Added SRV record lookup support
* Decreased max enchantment level from 50 to 30
* The /tp command can now send players to a specific coordinate
* Mobs can spawn on flat surfaces (such as up-side-down stairs)
* Updated language files
* Mobs are much less likely to glitch through blocks
* Server list can be reordered
* Nearby items in the world will auto-stack
* Stars are smaller and brighter
* Sky color in The End has been changed
* The o pick blocko functionality has been improved
* Certain items that previously wasno t stackable can now be stacked
* Hill biomes are slightly taller
* Wooden log blocks can now be placed side-ways
* Wooden half-blocks now act as wood
* Water slowly drips through leaves during rain
* Minecarts and boats will be placed by dispensers, if possible
* Gravel texture has been modified
* Levers can be placed in the roof
* Creeperso explosions damage is now modified by difficulty
* Performance improvements
* Other bug fixeso ¦
- Removed Herobrine