Not only do we get to look forward for a new 25-man instance, but also some very interesting changes, check the details below.

Excerpts of 2.4 Patch Notes (Full post)
Dungeons and Raids
* All 25- player raid bosses that drop set tokens will now drop and additional token!
* Gems obtained through Heroic difficulty instances are no longer Unique-equipped.
* 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.
* Scale of the Sands reputation will now be awarded in Hyjal at a much higher rate.

2.4 Raiding Improvements (Full post)
We have a few changes planned for patch 2.4 that we'd like to share a little bit with you. First, all 25-player raid bosses will drop more gold and those who dropped set tokens will drop one additional token. Additionally, the the loot dropped by Doomlord Kazzak and Doomwalker has been changed to bind-on-equip. These two outdoor raid bosses will also drop much more gold than before as well.
Lastly, Scale of the Sands reputation will now be awarded in Hyjal at a much higher.

Diminishing Returns Removed from Honor in 2.4 (Full post)
Currently, diminishing returns are applied to all honorable kills. What diminishing returns mean for honor is that each subsequent kill of the same target will reward you with less and less honor; 10% less per kill to be exact. One of the major downsides to diminishing returns is that the calculations, for potentially hundreds of thousands of players, is too intense to do real time, so they are calculated during off-peak hours. This in turn requires that the honor you gain be temporarily displayed as "estimated" until the calculations are run. It's a system that we've certainly improved (moving the calculation from weekly to daily) but still always disliked. It creates a very uninteresting and sometimes aggravating or confusing detachment from your achievements and the actual reward.

Spell Haste will reduce the global cool down on spells (Full post)
In 2.4, Spell Haste will reduce the global cool down on spells, down to a minimum of 1 second. It won't apply to melee and ranged abilities though however.

Fear ward in Shadow form (Full post)
Maybe being able to use Fear Ward while in Shadow Form would help? Yeah, I like this idea, we'll roll with it in the next patch.

Transmute: Void Crystal into Large Prismatic (Full post)
You're pretty close, but it's actually going to be a part of Enchanting. 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.

This helps reduce the exorbitant prices currently being seen for Large Prismatics, and helps raise the value of the Void Crystals. While this is the only change planned in 2.4 to help the Void Crystal prices, we're still looking at the possibility of additional 'help' for Void Crystal value in the future.

Ritual of summoning changed (Full post)
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.

Superior quality PvP gear off of reputation vendors (Full post)
We are tossing a little more into the mix with a change that is being implemented in patch 2.4. Players will be able to purchase level 70 Superior quality PvP gear off of reputation vendors.
We want both PvE and PvP to work together and this is just one way we think will help do that for those looking to better combine the two.

Warrior: Off-hand weapon critical hits from Whirlwind trigger Flurry and Rampage (Full post)
While I agree there is no exact number to shoot for in crit, in 2.4 we plan to make the off-hand weapon critical hits from Whirlwind trigger Flurry and Rampage which should improve damage a bit.

Shaman: Healing Grace (Full post)
One thing that will help is that in patch 2.4, healing grace will reduce the chance that all of your spells will be dispelled by 10/20/30%.

Arena: Shadow sight changed (Full post)
We have another change to the Arena that could alter things some as well. I thought it would be worth noting that we've made a change to Shadow Sight in patch 2.4. It 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.

Lots of more changes will probably be announced during the next couple of days, so stay tuned for more juicy details on the 2.4 patch!