I assumed the changes would be minor, like more dust coming from every disenchantment, but the MMO-Champion forums has compiled a list that surprises me quite a bit. It actually is a pretty sweeping change, reducing the material costs of a whole load of enchantments. Dust isn't the only thing targeted, they use less materials across the board.
In some cases, the material costs are halved, or more than halved. It's definitely not a small little change to Enchanting, waiting until the patch to enchant your gear will save you hundreds of gold. If you want to play it safe or are just curious, MMO-Champion has the full list for your perusal.