Minecraft 1.3: SinglePlayer Will be Turned into a Shell of its Former Self

This Minecraft 1.3 update on August 1st is going to be a doozy. The biggest change will be a complete upheaval of how single-player Minecraft works. "We’ve kicked out single-player, and made it a shell on top of multi-player," says Jens Bergensten on the official Mojang blog. For gamers, this means fewer bugs both while playing alone and with friends, as well as the ability to share your single-player worlds with anyone on your local network. It does require your PC to have a little more power, but Mojang has promised optimization in future updates.
Other updates include the new resource Emerald (which you can use as currency to buy items from villagers), books you can write in, tripwire for traps, a slew of new craftable items, and some new sub-biomes like Desert Hills (seen above) or Ice Mountains. For anyone who feels a bit overwhelmed by the relatively unwelcoming world of Minecraft, Mojang will be adding a "bonus chest," which will help players get started in their worlds, presumably fill with tools and other resources. Be sure to check out the full Minecraft 1.3 patch notes on this Reddit thread.
What new feature are you most looking forward to? With the introduction of Emerald, how long do you think it will take until someone figures out how to make a lightsaber? Or how much fun do you think it will be to grief your friends by setting up traps all over their world? Let us know what you plan to do with the changes in Minecraft 1.3