Here's a list of the known issues in the 2.3.3 patch (it continues after 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.
- The Gnome racial ability Escape Artist does not remove the Unstable Cloud debuff.
- Deleted characters take up space in an arena team.
-Male Blood Elves do not blink.
-The Gnome racial ability Escape Artist does not remove the Unstable Cloud debuff. 

Looks like some realms on the Bloodlust and Blackout battlegroups got hit with some latency...

We are aware of high latency and disconnect issues on the Blackout and Bloodlust battlegroup realms. We are investigating the cause of this issue and hope to have this resolved as soon as possible.

We thank you for your patience and apologise for the inconvenience caused.

• 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.
• The Gnome racial ability Escape Artist does not remove the Unstable Cloud debuff.
• Deleted characters take up space in an arena team.

Are you having issues handshaking successfully? Someone posted the fixes for both Windows XP and Vista in the official forums:

1) Close the game.

2) In Windows click Start, run..., in the window type

cmd

press enter.

3) In the new window type

ipconfig /flushdns

Alternatively, go to "My Computer" -> "Control Panel" -> "Network Conections" -> right click your LAN or Wireless Connection -> Select Disable, then re-enable it.

If you are still unsuccessful, reset your modem/router, then perform the instructions again. As explained below in the thread, some ISP's hold the cached DNS data for longer periods of time, therefore this will not work for you YET. There isn't much you can do apart from trying again later.

Mac version by Triselley in a post below.

Close WoW.

Open Terminal.app in /Applications/Utilities

Type:

lookupd -flushcache

For Windows Vista (why would you EVER run Vista...)

1. Click the Microsoft Vista Start logo in the bottom left corner of the screen
2. Click All Programs
3. Click Accessories
4. RIGHT-click on Command Prompt
5. Select Run As Administrator
6. In the command window type the following and then hit enter: ipconfig /flushdns 

Apparently Blizzard are still working on realm stability issues, although I must say I haven't noticed anything wrong!

Blizzard poster Crezax has just posted an update saying that yesterday's World of Warcraft patch not only implemented several content updates and bug fixes, it also "implemented some background tweaks to specifically improve stability across all realms and especially instances."

Apparently some realms had issues earlier today... heres's the dealio, gotta love Blizzard actually updating us on outages now!

Update - 4:21 PM After issuing a restart, Rexxar is online and accepting players. We will continue to monitor for performance issues. Thank you for bearing with us.

Update - 3:48 PM Rexxar is continuing to drop players. We are working to get this last realm stable.

Update - 3:39 PM Rexxar appears to have dropped all players, but is recovering. The other listed realms are steadily seeing an increase in population.

Update - 3:21 PM Currently, all of the listed realms are back on line and seeing increasing population. We are continuing to monitor performance on these realms. Logging back into these realms may take some time, due to traffic.

Update - 2:59 PM We are continuing to work on this matter as quickly as able. We will continue to provide half-hour updates as this issue progresses. Thank you for bearing with us.
-------------------------------------------------------
We're aware that the following realms are currently experiencing issues that are disconnecting players or keeping players from connecting. Our network and database administrators are currently working to resolve this issue as soon as possible. We'll provide an update in approximately 30 minutes. 

I've got this quite a bit since Burning Crusade was released, but haven't cared so much since I thought Blizzard handled the release of BC so well. However, they are apparently on top of all these latest crashes, issues and bugs.

We are aware that certain realms are experiencing performance issues such as continent crashes, "world server down" errors, and instance crashes, primarily during peak hours. We’re monitoring these realms very closely and have already applied various fixes, and additional fixes are being tested as we speak. As always, we appreciate your patience and support with these issues; we'll continue to provide updates as more information becomes available.

WoW Insider has a pretty decent summary of all the main issues with the coming of the new patch. For me, it was constantly being disconnected, just straight dropped from my server.

I'm glad to see that the extended extended maintenance wasn't too bad though!