Unconfirmed: It seems that Weapons will produce more Hypnotic Dust and Armor Essences, which is the opposite of how it's been. Take this to note.
Everyone knows how to disenchant for profit so I'm not going to explain any of that. With the release of Cata everyone is hurrying to level up their professions and noobs are placing GREEN items on the AH for what they think is a good price.
With the essence/dust prices the way they are there is a HUGE potential to make gains on the AH.
*Be cautious of iLvl when buying level 80 greens. Only buy the greens ilvl280+.
*It seems tailors are flooding the AH with deathsilk pieces.
Hypnotic Dust: 25g EACH
Lesser Celestial: 14g EACH
Deathsilk pieces: 20g
Disenchanting info for 3 deathsilk pieces:
Deathsilk Boots - Item - World of Warcraft
Deathsilk Belt - Item - World of Warcraft
Deathsilk Bracers - Item - World of Warcraft
This profit margin want last long so make good use of it.