(This was posted live as the demo was going on.)
During the announcement of Diablo 3, Blizzard gave a brief demo. Unfortunately, it's not available for play.
The Lead Designer of Diablo 3 is giving the first public demo of the game. He begins by introducing the barbarian class and showcasing where Diablo 3 retains the stylistic feel of the first two in the series but expands upon them. There is now a hotbar where the potions used to be and you can switch skills with both tab and the mouse wheel.
The world is destructible and you can use it to your advantage. In the demo, he used a wall to destroy a zombie horde.
A new class, the witch doctor, is introduced. He primarily relies on pets to do his dirty work, the first of which is the Mongrel.
Some of our old friends make appearances as well. Deckard Cain is alive and well and even helps you with part of a dungeon.
Full armor sets have been customized for each class.
Diablo 3 is aimed to be a highly cooperative game.
For an early demo, this looks like something to keep an eye on.