Update - The patch notes have been updated once again with the resilience changes and more class changes. New additions have been marked in the notes below!

World of Warcraft PTR Patch 4.1 - Updated February 28th
Originally Posted by Blizzard(Source)x - Notes added in the 2nd notes update of the day.
GeneralFlying mounts can now be used in Ghostlands.x Resilience scaling has been modified for linear returns, as opposed to increasing returns. Under the new formula, going from 30 resilience to 40 resilience gives players the same increase to survivability as going from 0 to 10. Resilience now scales in the same way armor and magic resistances do. A player with 32.5% damage reduction from resilience in 4.0.6 should see their damage reduction unchanged in 4.1. Those with less than 32.5% will gain slightly. Those with more will lose some damage reduction, increasingly so as their resilience climbs.
Classes

Update Patch 4.1 PTR - Official Notes Update
The Patch 4.1 PTR Notes have been updated once again with the 2 missing changes from build 13698.
Originally Posted by Blizzard(Source)

Patch 4.0.6 Hotfixes - March 1
Originally Posted by Blizzard(Source)Here you'll find a list of hotfixes that address various issues related to the recently released World of Warcraft: Cataclysm patch 4.0.6. Hotfixes are updates we make on our end without requiring you to download a new patch. Some of the hotfixes below will go live the moment they are implemented, while others may require your realm to be restarted to go into effect. Please keep in mind that some issues cannot be addressed without a client-side patch update. We will continue to update this thread in the days ahead as additional hotfixes are applied. Visit our Bug Report forum for a list of 4.0.6 known issues.

PvPFlag carriers in rated Battlegrounds now take 25% more damage from all magical and physical attacks. The 25% additional damage from carrying the flag stacks with the Focus and Brutal Assault debuffs. Flag carriers in normal Battlegrounds are not affected by this change.
Quest & Creatures
Tol Barad PeninsulaThe quest "Walk A Mile In Their Shoes" has not always been correctly awarding players with quest credit after completing the escort event. This quest is being temporarily disabled and removed from the achievement criteria for Just Another Day in Tol Barad. This fix will require a realm restart to take effect.
Blue Posts
Originally Posted by Blizzard Entertainment
Changes to Ambassador Title in 4.1
If you have the achievement you'll keep the title. The Exalted worked differently because we wanted to move the title to a different achievement altogether (50 exalted).

In this case, if you have the achievement you'll keep the title. If you're close to getting the achievement, you might want to hurry and get it before 4.1 because after 4.1 you'd need to also gain the additional rep to meet the requirements, earn the achievement, and get the title.

Same as it was for Loremaster or Explorer, if you had the achievement you still have the achievement, even though the requirements changed. (Source)

Zul'aman and Zul'gurub
There's a lot of new content in Cataclysm. There's also a plethora of updated content to advance the story.

Likewise, there's plenty of new content still to come in this expansion. But, we're also going to keep moving existing themes forward when the story calls for it. There were specific reasons for originally entering Zul'Gurub and Zul'Aman, but those reasons by no means wrap up the story of the ancient troll empire. These city ruins still serve a major purpose in troll lore, beyond just providing new locations to gain loot.

We're moving the story of the troll nations forward, and hope you recognize and enjoy that. Hakkar and Zul'jin are gone now. Even so, that doesn't make Zul'Gurub and Zul'Aman irrelevant as key locations of Azeroth.

A few forum threads appeared on the forums (nice work on Datamining the legendary staff!), people asked me tons of questions, it's time to try to do a preview of the legendary staff!

Disclaimer
This is not an official preview, the whole post could just be speculation going wrong. There is definitely a lot of data available and it's definitely enough to assume that this is indeed the legendary staff but unless you hear it from a blue poster, anything I post could be a giant lie.

In any case, nothing is official, nothing is final, this is just data from a test server.


Weapon Model
The staff has 3 models and we can assume that it will be upgraded through multiple quests/events like Shadowmourne. The upgraded is much more visible than with Shadowmourne and it looks like you will even add parts to your staff at some point.

A new build might be deployed on test realms soon apparently, it's a fairly minor build and I had time to have fun with something else, more on that a little later ...

What I've been suspecting for a while is now confirmed, Firelands will not be included in patch 4.1. This is why you aren't seeing anything about it in the patch notes or on the test realms.

For more details on the decision, read the Full Article on Eurogamer.net

We now have a very official blue post for the information, Firelands is not part of Patch 4.1. See the previous news post for more information.

Firelands raid will not be in Patch 4.1
Originally Posted by Bashiok(Source)By now you’ve seen that the redesigned Heroic five-player dungeon versions of Zul'Aman and Zul'Gurub are on the PTR, featuring all-new boss mechanics, updated epic-level loot, and some rare mounts for players to try to tame.

You may be asking, "where's Firelands?