Okay so in case you don't feel like searching through WoW.com front page (slacker) here is a copy and paste about what is known so far regarding the incoming stat changes for the new expansion Cataclysm.
Attack Power on gear is gone. Instead, some classes will get 2 AP from each point of Agi (Rogues, Hunters, Shamans, Druids), and other classes (presumably Warriors, Paladins, and Death Knights) will get 2 AP per point of Strength. Side effect: no more plate wearers stealing your gear
Spell Power is gone. It comes from Int now.
MP5 is gone. Spirit is the mana regen stat, and all classes that need it will get some form of Meditation. (Hunters, never fear - you don't use mana any more. More on this in a separate post.)
Armor Penetration is gone. That one was just confusing.
Defense is gone. Tanks are now defense-capped from talents, like Druid tanks.
Haste now increases your rate of resource regeneration (mana, energy, rage, runes, focus).
Block Value is gone, but blocks now mitigate a percentage of damage.
Stamina is going to be more equal across different armor types - no more "plate HP envy."
This is one of those changes about which I'm totally on the fence. On the one hand, it makes a lot of sense. We have these basic stats, and really, everything else should be derived from the stats. Wow is based on D&D, and that's essentially how D&D works. Attack Power has always been based on Agility or Strength depending on class anyway, so there was really no need for excess AP stats. I never understood Armor Penetration (in my defense, I'm more the caster type dammit, don't call me a noob!). The Block Value eradication, and change of Block makes more sense to me too. I am cheering about Spirit becoming the main point of mana regen again (although a little irritated that they just nerfed spirit by buffing mp5, when they are making such a change in the expansion... but then again, let's all remember that despite all the excitement, Cataclysm is still a long way off). The fact that Hunters needed mana was stupid, I really like the idea of it going to focus, theres more similarity with their pets. I think it's pretty clever how haste is changing - I always thought it should be that way instead. Intellect should be the basis for more caster abilities, such as spellpower.
Now, another incoming addition for Professions is the ability to "Reforge", which will be specificly based on your profession. I.e., Tailors can reforge cloth items, Blacksmiths plate, etc. Reforging is the ability to readjust some of the stats on an item. For instance, if a cloth piece drops with 50 Spirit and 40 Stamina, I can reforge it to make it have 10 Intellect, 40 Spirit, and 40 Stamina. No word yet on the limitations regarding amount, however, you will not be able to add to a stat that is already on the item (So while I can add 10 Intellect, I cannot take 10 points from stamina to make 60 Spirit.)
Okay, now that i've covered those basics, here are the problems I foresee. In TBC, there was so much variety and specific stats on items, that it was not uncommon for an item to drop that was no good for anyone. Then they combined melee and spell haste into simply haste, and same for crit and +healing/+damage into spellpower. This simplification really changed the way gear dropped in raids - there was a lot more competition for each item. I don't think that's a bad thing... it's painful to disenchant some really nice items.
But now it's going even further. Without knowing what limitations they are going to put on reforging, I could pick up any cloth item (after all, armor class is still important) and remove stats on it to add stats that are important to me. So, in the extreme, all that really seems to matter is what armor class it is, and what slot? This is frighteningly generic to me. There have already been a lot of complaints in Wrath about how generic items seem to be (at least the artwork... how many different versions/colors of that damn Moonshroud Robe has my priest worn anyway?) It's too soon to tell for sure, or to get too worked up over it though. I'm working off of a very small amount of details at this point, but so far I am a little concerned.
All this information is derived from the first "Class, Items, and Professions" panel yesterday. There is a second one at 2:30 PST today, and I am waiting with baited breath for that one. I have a lot of ranting I want to do about Path of the Titans as well, but I'm hoping there will be more clarification at tonight's panel, so I'll hold off on my comments for that. The classes discussed yesterday were Hunter, Priest, Shaman, and Warrior. There weren't a whole lot of details, and it was pretty disappointing. I think the most exciting news so far class-wise was for hunters.