Only 6 days and counting until The Burning Crusade is unleashed upon the world, and the Dark Portal is finally open. All this week, certain events will be taking place throughout the world. If you venture to the Dark Portal in the Blasted Lands, demons are starting to spawn through the Portal. There is a quest to help kill them, and in return you get some gold and a [Tabard of the Protector]. Make sure you get a group first... not because it's hard to kill the demons, but just so you have a better chance of tagging them before anybody else. There will be a lot of people standing around the Portal casting AoE all the time, and they only spawn a few at a time.

Also, one final patch has been released before the Expansion comes out. Here's an blurb from it:

Patch 2.0.3 Wrote:

Several years have passed since the Burning Legion's defeat at the Battle of Mount Hyjal - and the races of Azeroth have continued to rebuild their once shattered kingdoms. With renewed strength, the heros of the Horde and Alliance have begun to explore the broken lands beyond the Dark Portal. What dangers or rewards await mortal champions in Draenor? And what will the Alliance and Horde do when they discover that the demons they thought vanquished have returned to renew their terrible Burning Crusade?

After you install The Burning Crusade, you will have to re-patch 2.0.3, so don't delete the files just yet. The game CDs went into production right before the patch was ready.