Since the snapshot yesterday we’ve fixed some bugs that were reported, as well as including new sound effects for the Wither, bats, the anvil and finally the Ender Dragon!
I started playing the latest snapshot (12w42b) and... well, I thought I read that slab lighting was fixed?
[img]https://dl.dropbox.com/u/12906062/minecraft/lighting.png[/img]
Looks pretty fixed to me.
There's still some (very very minor) errors in the world gen lighting, too.
[img]https://dl.dropbox.com/u/12906062/minecraft/lighting2.png[/img]
They're not nearly as bad as they used to be, though. New worlds all.
The lighting fixes Dinnerbone did fixed lighting, but they were very process intensive, especially in the Nether with all the light-emitting lava source blocks. Since 1.4's release was nearing, they decided to revert the lighting changes and try again in 1.5. I've heard they are rewriting rendering code completely among other things - so maybe they are basically rebuilding major parts of the game so as such fixes will work without tearing the game apart...