There's a huge preview of Warcraft III over at Gamespot packed with new information, screens and food for the youngens:
.. Another RPG-like element for the heroes is inventory. Heroes will be able to hold only one item at a time, but this could be a special item, a weapon, or a quest item. The key to the drawbridge in the quest mentioned on the previous page is one example of a quest item that a hero might hold in his inventory.
Heroes will of course be your prized units, and you'll want to keep them alive. However, because Blizzard doesn't want you to dread their deaths and thus hold them back from battle, it will be easy for you to resurrect them if they do fall. When a hero dies, he returns to the Altar of the Heroes. Here, you can pay gold to resurrect the hero or simply recruit a new one. And should you ever want to return to a hero you abandoned earlier, the hero will always remain at the altar for you to reclaim.