My two cents, as will be shared in our podcast later this week...
With everything else Blizzard has going on, and with the problems they have had in the past with the F/F Alpha (leaked clients, info, etc), and with how fast official information is coming out... I would bet this is first round beta. Adjusted slightly, so it's just Friends, Family, and maybe some exceptional players or what not chosen specifically by employees. But still, a beta build of the game. All signs point to it being a beta.
That's not to say it's coming out sooner, but...
May 4th - F/F Beta Test begins
July 6 - "Second Phase" Polished Beta Begins
July 6 - Aug 3rd: Opt-Ins Allowed in Waves
August 3rd - "Open" (As open as they make it, possibly just the opt-ins)
Friday Oct 21'st - Opening event coinciding with Blizzcon, possibly when Deathwings makes his emergency
Tuesday October 26th - CATACLYSM