http://www.wow.com/2010/03/01/cataclysm-stat-and-system-changes-revealed/A few of the more major points:
Stamina -- Non-plate wearers will have a lot more.
Spirit -- Only found on healing gear.
Intellect -- Grants spell power.
MP5 -- Gone completely.
Spell power -- Only on weapons, and just to make them clearly a caster item.
Attack power -- Gone on most items.
Parry -- No longer provides 100% avoidance and no longer speeds up attack.
Resilience -- Only affects player damage and player crit damage, no impact on crit chance, mana drains, etc...
Block Value -- Gone, 30% passive block value now when wearing a shield.
Weapon Skill -- Gone completely.
Gem Color -- Few stats changing. Hit will likely become a blue gem (it's yellow now).
Defense -- Gone, becomes dodge, parry, or block rating.
Reforging -- You'll be able to reforge gear to customize your stats -- 50% of stat X can become stat Y. Restrictions apply (no Stamina->Strength, for instance).
WoW developer Twitter chat transcript, sorted by category
http://www.wow.com/2010/02/26/wow-developer-twitter-chat-transcript-sorted-by-category/