From the announcement:
What does it mean now that the Athenians are unlocked? We already have rules and art for the Athenians, now we can proceed with the sculpting of the miniatures. By this time next year, we'll have a completed Athenians Warband Starter Set, Hoplite Unit, Peltast Unit, Archer Unit, Swordsman Unit, Hero with Armor Rack and Captain with Casualty. You may now select these as an option for your rewards on Kickstarter, but they will be shipped with the book in July 2014.