Here's a sample of all the known issues in patch 2.3. For the full list make the jump...

General
-Dwarven racial Find Treasure is deactivated on death.
-Undead Males main hand weapon is appearing larger than previous builds.
-Equipping a thrown weapon while in the middle of an Auto-Shot will cause animation issues. 

There are some undocumented changes in the 2.3 patch, here's some of what WoW Insider found with more after the jump...

• Boats and zeppelins which carry players now have NPC crews, including vendors.
• There is a new neutral flight path outside of Zul'Aman, which means you can now fly out from Silvermoon City.
• Whoever in a group has loot rights to a corpse will appear on the minimap (LOOT THE DOG!)
• There is now a log in the guild information tab that allows you to see promotions, kicks, joins and leaves.
• Mousing over the mail icon will show you the name of the mail sender.
• Track Humanoids distinguishes between friendly and hostile targets.

Clarifications on the changes coming with global cooldowns, stop casting, and all that with patch 2.3:

In 2.3 you don't need /stopcasting, you can always try to cast before the end of your current cast. This gets the cast to the server sooner so it's more likely that your casts will go back to back.

A couple things to note:
* The global cooldown is client side, and you can never cast more often than the global cooldown (when it's triggered)
* This doesn't reduce your cast time. If you send your cast too early, it'll still fail because another spell is in progress.
* Careful timing is always better than spamming. Prior to 2.3, you were always penalized by your latency when casting. Now you're only penalized if you cast too early. :) People who used to use /stopcasting are familiar with this, but now the penalty is simply a round trip from the server instead of canceling your previous spell.

Are experience changes on the realms changing the experience gained by pets? No:

    * Pets still require 25% of the experience that a player would at the same level. Players now require less experience to level between levels 20 and 60, and so our pets also require less experience during those levels.
    * Pets still do not get any share of the experience when their owner completes a quest. (I didn’t expect they would, but it was worth checking.)
    * As on live, pets do not get experience when they kill something that is grey to the hunter.
    * The experience that pets get per kill does not appear to have changed.
 

Can't be too long now...

Sunwell is coming along nicely. It will be on the PTR shortly after 2.3 goes to the live realms. We still need to perfect 2.3 a bit on the PTR.

The 5 person dungeon is complete and the 25 person raid instance is progressing nicely. There's also a cool "public" area featuring brand new daily quests called Sunwell Isle.