Zolphea (German Blue poster) posted some noteworthy info about Sunwell and Tier 7 level gear. (Source)

In the 25-man dungeon you will be able to receive Tier 7 gear. These Items will look similar for the different classes. There will be different colors but no unique design per class.
There will be more than 3 Bosses. When 2.4 will hit the PTR isnt determined yet.

Zolphea also posted additionnal info on Magister's Terrace.

Magister's Terrace difficulty will be above shadow labyrinth and shattered halls.
Normal: 3 bosses ilvl 115 loot, 1 boss low karazhan epic loot.
Heroic: 3 bosses low kara epic loot, endboss will have malchezaar equivalent epic loot.

The first 3 bosses will have 15 slot loot table, endboss 10 slot epic loot table.

Sunwell
* From what we learned the first boss of Sunwell is supposed to be a rigid gear check along the lines of how Patchwerk was (not that it's a similar fight, just a gear type fight). Also there is a demon/dragon type fight where you take portals between two worlds of the boss. The last one sounds cool, but we didnt get more details.
* According to our reasoning and the info we got (see above for explanations), Sunwell loot picture (link) seems to be true, also we believe these items are from an early beta (i.e. the phase where they decide stats, names etc...) which could partially explain spelling errors.

Arena Season 4
* Arena Season 4 armor sets will be titled "Brutal Gladiator".

Quote from Blizzard staff
General
Characters will now retain talented spell ranks so when they retalent they do not have to relearn the spells from trainers. (Source)
Spell Haste: Spell haste now reduces the global cooldown on spells, down to a minimum of 1 second. This change does not apply to melee and ranged abilities. (Source)
Patch 2.4 will remove the restriction for Ritual of Summoning that prevents you from summoning players into instances. Provided the player meets the instance requirements, you'll be able to summon them in from anywhere in the world. (Source)

Items
Once every 24 hours, through Enchanting (not Alchemy) you'll be able to split a Void Crystal into two Large Prismatic Shards. This is through a new recipe that's being added in 2.4. (Source)
Gems obtained through Heroic difficulty instances are no longer Unique-equipped. (Source)
Players will now be able to purchase level 70 Superior quality (blue) PvP items from reputation vendors in Outland. (Source)
Items intended for Retribution Paladins have had their stats adjusted. Retribution Paladins should see an increase in dps as a result. (Source)
Players can now only carry 80 Conjured Manna Biscuits at a time. (Source)

PvP
Arenas
Shadow Sight in patch 2.4 is now going to increase damage taken by 5% rather than dealing damage over time. The duration has also been reduced from 21 seconds to 15 seconds. (Source)

PvP
Players will now be able to purchase level 70 Superior quality (blue) PvP items from reputation vendors in Outland. (Source)
We've reached a point where we're now confident that applying diminishing returns to honor is no longer necessary, and we're currently planning to remove it with the 2.4 patch. (Source)
Players that have the resurrection sickness debuff will not be worth any honor, and if a player dies 50 times or more during a battleground they won’t be worth any honor for the remainder of that battle. (Source)
What the removal of diminishing returns means for you is that as soon as you defeat an opponent that rewards you honor, you will receive that honor, and you will be able to spend it right then. There will no longer be an estimate, and you will no longer need to wait until the next day until you can actually spend it. Your achievements through honor-based PvP will be instantaneous. (Source)

Dungeons and Raids
All 25-player raid bosses that drop set tokens will now drop an additional token! (Source)
All 25-player raid bosses will drop more gold. (Source)
Gems obtained through Heroic difficulty instances are no longer Unique-equipped. (Source)
Loot dropped by Doomlord Kazzak and Doomwalker has been changed to Bind on Equip. In addition, the cash dropped by these bosses has been significantly increased. (Source)
Scale of the Sands reputation will now be awarded in Hyjal at a much higher rate. (Source)

Professions
A new daily quest will be added for fishing. It's available from "the mysterious old man" near Silmyr Lake outside of Shattrath. (Source)

Interface
When you loot a Bind on Pickup item that only you can pick up (such as Heroic Badges) you'll no longer see the confirmation dialog. (Source)
When you loot a Bind of Pickup item the confirmation window is going to list the name of the item in the window/ (Source)

Druid
The Feral bears will be seeing an improvement with Lacerate dealing additional damage based on your attack power. (Source)

Hunter

Mage
Spellsteal will no longer overwrite a longer duration buff. (Source)
Players can now only carry 80 Conjured Manna Biscuits at a time. (Source)

Paladin
Items intended for Retribution Paladins have had their stats adjusted. Retribution Paladins should see an increase in dps as a result.

Priest
Priests will now be able to use Fear Ward while in Shadow Form. (Source)

Rogue

Shaman
Healing grace will reduce the chance that all of your spells will be dispelled by 10/20/30%. (Source)

Warlock
Patch 2.4 will remove the restriction for Ritual of Summoning that prevents you from summoning players into instances. Provided the player meets the instance requirements, you'll be able to summon them in from anywhere in the world. (Source)

Warrior
Endless rage will now yields the correct amount of rage (25%). (Source)
Off-hand weapon can now critical hits from Whirlwind trigger Flurry and Rampage (Source)