Diablo 3 accidentally goes open beta

Since the early hours of this morning, Diablo 3 fans have had the opportunity to take part in the Diablo 3 Beta without having access to the Beta.
When Blizzard launched patch 17 last night, they appear to have left a hole that would allow players to play the beta by having a battle.net account, creating a battle tag in the account settings and downloading the client.
In the past few minutes, Blizzard appear to have pulled down the servers now and postred an official note saying the Beta is now down for maintenance, looks like they caught on.
Source: Diablo: IncGamers