Basically something changed last night in way your ISP looks up where blizzards server is on the internet, this happens all the time around the world for websites/games etc and thats why DNS(domain name servers) exist.
The issue is DNS servers use a cashed(stored) copy of what they lookup and only check for changes when they update which can be anywhere between an every hour to every 2 days. Thats where ANZ is hitting the issue waiting for the DNS to check for changes.
The patch itself didn't cause this, something else did whether blizzard changed the physical servers or AT&T changed some routing or such.
Your ISPs DNS server CAN NOT be updated by blizzard, however it does auto update itself so the issue will fix itself in time. This issue is caused by ANZ ISPs doing things differently to the rest of the world, Blizzard did not know or expect this.
If you wish to play in the mean time google offer a free public DNS server, below is instructions on how to change your DNS to this server.
Changing DNS server settings on Microsoft Windows 7
Go the Control Panel.
Click Network and Internet, then Network and Sharing Center, and click Change adapter settings.
Select the connection for which you want to configure Google Public DNS. For example:
To change the settings for an Ethernet connection, right-click Local Area Connection, and click Properties.
To change the settings for a wireless connection, right-click Wireless Network Connection, and click Properties.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Select the Networking tab. Under This connection uses the following items, select Internet Protocol Version 4 (TCP/IPv4) or Internet Protocol Version 6 (TCP/IPv6) and then click Properties.
Click Advanced and select the DNS tab. If there are any DNS server IP addresses listed there, write them down for future reference, and remove them from this window.
Select Use the following DNS server addresses. If there are any IP addresses listed in the Preferred DNS server or Alternate DNS server, write them down for future reference.
Replace those addresses with the IP addresses of the Google DNS servers:
For IPv4: 126.96.36.199 and/or 188.8.131.52.
For IPv6: 2001:4860:4860::8888 and/or 2001:4860:4860::8844
Restart the connection you selected in step 3.
Test that your setup is working correctly; see Testing your new settings below.
Repeat the procedure for additional network connections you want to change.
Twitter: @Narull | ANZ Diablo III MVP
http://us.battle.net/d3/en/forum/topic/6490399005 - Narull's Hardcore Challenge.
There not spelling mistakes, Im speaking 'Ye Old English'