The recent Magic announcement was at PAX East this past weekend during the Magic Panel wherein the September’s new set: Theros was revealed. They also announced the two other sets in the Theros block: the February, 2014, set which was code-named “Romans,” is called Born of the Gods and the May, 2014, set, code-named “Countrymen,” is called Journey Into Nyx.

Set Name: Theros
Block: Set 1 of 3 in the Theros block
Number of Cards: 249
Prerelease Events: September 21-22, 2013
Release Date: September 27, 2013
Launch Weekend: September 27-29, 2013
Pro Tour Theros Dates: October 11-13, 2013
Game Day: October 19-20, 2013
Official Three-Letter Code: THS

More set details here.