It appears that the Mass Effect 3 Beta might of been leaked, or there is a private beta that has started!
Members of the Xbox Pre Release are getting a tile on their dashboard that leads to a download for the beta.
More to come!
UPDATE: Seems the leak/beta also has single player!
The leak lets players make a new character and play through the start of Mass Effect 3. Including a huge spoiler that can not be posted here. Still unclear if this is a beta, or a leak!