List of Items I will Stockpile for Cataclysm

Old world materials for all professions from skill level 1 to 50.
Early outland materials.
Twink weapon and chest enchanting scrolls.
Wrath enchanting mats.

Let's look at my reasoning behind these items.

Old world materials for skill level 1 to 50, particularly herbs used in alchemy for goblins, will make a lot of money early on in cataclysm. Players making their goblins or worgs will focus on powerleveling professions either as they level or once they hit 80, so I am not going to be trying to sell everything during the week of the release. Regardless of how well stuff sells, I will save 50% of my goods for inflation to kick in. This way my copper ore going for 5 gold a stack will probably be worth 10 gold or more per stack later on in the expansion. Next we have outland materials, since I assume outland will not change very much and all the materials from outland will not also be found in the "new" azeroth, these materials should go up with inflation. Twink weapons and chest enchants will sell great the first few weeks of cataclysm and I expect to sell a hundred or so of these babies. Firey, crusader, health to chest, etc.

Wrath enchanting mats are a bit tricky and a total gamble. I believe that inflation is going to take hold of these materials later on in cataclysm and so you will see decent prices that are atleast more than what they are now. I expect the rate of inflation to be 2 to 8 times the current values we are seeing now. That means that if I am correct that 100 infinite dust for 90 gold now will be worth as much as 720 gold in cataclysm about midway through.