i hope you people who think its duel wielding know your wrong... notch already stated that duel wielding is NOT going to be implemented in Minecraft.... but besides that looks like obviously the new chest and possably the ability to change into lefty mode?? perhaps hinting at character customization??
Look again.... The default sun is bigger then it is now.
Also the vines are not what you think. People have been adding vines to minecraft since before Terraria. If it was a add mod like adventure craft or simple as changing the ladders to vines. And even if somethings are taken from Terraria He stated that he was going to compete with Terraria.
Cactus shape guesses are wrong too.
Look closer. That is just some terrain in front of the cactus. If you look you can see it's 2 blocks lower than the chest. what your seeing is a block of sand in front of the cactus.