Been Lucky for once! Apparently if you played since vanilla and signed up for annual pass right when Morhaime announced it in 21.10.2011 you have good chances of getting in with the first wave.
Troubles
I had so much trouble with annual pass, had to order the annual pass 6 times so far. When Blizzard threatened to put our real names on the forums it seemed that parental controls with the posibility to opt out of real-id was the best way to not get plastered all around the web.
Haven’t touched or bothered with Parental controls ever since. The main account was protected by parental controls and the second account eligible for annual pass so they did not even ask me, or let me choose and attached the pass to the wrong account 
this was the first change I had to get done. Since then I lost the annual pass 5 more times, parental controls were removed twice. The pass kept vanishing and the worst part Blizzard did not bother to notify you about it.
A little bird whispered me that the BETA invites were rolling out “soon” and I happened to check the Account Management just to be sure. And yeah Annual pass was gone :-/ Since last saturday I had to order Annual Pass 3 times … the shortest one lasted a whole 60 minutes on my account.
The worst part is that Blizzard does not know what is causing this and there are many accounts affected. You better check your status.
“Referring to your call, we would like to confirm once again that you have entered the annual pass now and again we have changed the expiration date back to October 2011.
We deeply regret that the annual pass was removed again and again for no apparent reason, but please do not hesitate to contact us again.”
So I know you did not come for this, but I had to get it off my chest and maybe it helps some of you, who are no doubt eagerly awaiting your beta invitation.
Beta Invitation Mail
Here is how the invitation Mail looks. Iw as able to see the Beta Status a couple of hours sooner via the Account Management, might be faster to check there. Beware of SCAM Mails. Always check for the header of these Mails:
Received: from mx2.blizzard.com ([12.130.201.10]) by mx-ha.web.de (mxweb104) with ESMTP (Nemesis) id 0M3QUe-1SS6uu1J20-00r1WM for ; Thu, 22 Mar 2012 05:53:53 +0100
Scammer mails origin usually from gmail, yahoo, etc. Your best option is to never click links in blizzard mails and instead go to the account management!
Account Management
Here is what the Account management should look like. A new WoW Account should appear, labeled
“World of Warcraft®: Mists of Pandaria
[WoW]
Public Test Realm (PTR)”
Client Download & Character Copy
The next step is to select client download option and do initiate a character copy via account management. It appears that we have 5 character copies available at this stage. For now we can select only 1 Realm in the EU – Mekkatorque. I fear it is going to become really crowded
Anyway expect some shaman stuff, soon!
Lucky one
Now we are waiting for a lot of exciting post in your blog about Enhancement Shamans and Monks 
HF with MoP
@Murlyo
thanks! Been rendering a monk char creation video. Then the first few quests, while I look at shaman changes. Many things changed and I am trying to make the “best of it” atm.