Wooo! Minecraft 1.4 may be coming out on October 24!
It will not have the long-promised mod API, but now there are:
1) Invisibility potions.
2) Night vision potions.
3) Command blocks (play a pre-set command upon redstone signal).
4) More commands, some to go with the new blocks.
5) Carrots (including a golden version).
6) Potatoes (including a baked and poisonous version).
7) Beacons providing permanent buffs.
8) Wither bosses.
9) Wither skeletons.
10) Entities (e.g. Minecarts, mobs, boats, falling sand/gravel, dropped items, etc) are able to pass through portals.
11) Item frames.
12) Flower pots.
13) Carrot-on-a stick, allowing the control of ridden pigs.
Plus many more features! Wooo!