The latest developer build of Minecraft, which brings it up to 12w39b, has just been released by Mojang.
Nathan “Dinnerbone” Adams posted the links to the new build on Twitter, which you can read below:
12w39b is out, blogpost still needs to be edited. Minecraft.jar: assets.minecraft.net/12w39b/minecra… server: assets.minecraft.net/12w39b/minecra…
— Nathan Adams (@Dinnerbone) September 28, 2012
The development builds are not recommended for players who simply want to play the game, so grab them at your discretion. Here’s what you can expect in the latest build:
“Lots of block placement issues with lighting have been fixed, but nether is still sketchy. If I can't make the nether better, I'm reverting.”