http://notch.tumblr.com/post/5775170768/the-changelist-for-1-6hes already posted on his twitter "I forgot to add * Added Nether support to multiplayer! Seems like a big feature.. should be on the list!"
Some picks:
* Fixed minecarts next to each other causing extreme velocities (sorry!)
physics boosters broken now, probably because of the lag issues I pointed out with minecarts as it is. booster tracks have a top speed, physics boosters don't and are even more detrimental to servers.
* Fixed falling while riding not dealing damage to the rider
no more sick air on minecarts?
* Fixed a game crash when riding a vehicle or animal into the nether
so i can ride a vehicle through now? please be yes
+ Added server property view-distance. Sets the radius of terrain updates (in chunks) to send to the players. Range 3-15, default 10.
because he hasn't fixed the issues i've been ranting about
* Fixed creepers retaining charge level when they can’t see their target
phew
* Fixed ice so it regenerates regardless of whether it’s snowing or not
* Fixed rain falling through liquids
no more snow blindness underwater for burny
*Mushrooms now spreads (very) slowly
mushroom farming YAY
Only thing I can't see is it looks like sky dimension didn't make it in. So for 1.7 lets hope he gets sky dimension, pistons, and a proper implementation of network map updates
EDIT: * Fixed submerged boats rising very very fast
boat elevators nerfed

. chugs current base depends on a boat elevator lawl. Hes not going to be happy