Entertainment Weekly got the scoop. My Little Pony: Friendship is Magic will premiere Season 3 on Saturday, November 10, 2012 at 10 AM. The article does not say what time zone that is, but times are usually given as EST. The article goes on to give some more details about season 3 and the opening 2 parter featuring the ancient Crystal Empire that suddenly appears after a millennium of going missing. Meghan McCarthy is mentioned as saying that the season will prominently feature Twilight advancing in her studies as well as the ‘reemergance of a certain unnamed fan favorite villain’.
Since Twilight is BEST pony, I am certainly looking forward to what is in store for Season 3. And since John de Lancie has already confirmed that he has done some additional voice work for the show, it is not too far of a stretch to guess that his character, Discord, will return!