Zack Snyder has confirmed that there will in fact be a 300 prequel called Xerxes that he tenatively will direct.

Get the Big Picture says:

So now we’re here with a story about the Battle of Marathon. “The lead character is Themistocles,” said Miller upon completion of the graphic novel…The story is very different than 300 in that it involves Xerxes’ search for godhood. The existence of gods are presupposed in this story and the idea is that he’s well on his way to godhood by the end of the story.”
Snyder adds more to the backdrop:
“Themistocles is kind of the father of democracy. It’s much more about these guys choosing. The Spartans are, ‘We fight, we die,’ so that’s an easy choice for them, there’s no surrender. The cool thing about Themistocles and his gang is that it’s way more difficult. Things aren’t as clear or unchallenged. He has to be more political to get everyone to agree. It’s political, in the soap-opera sense of the word. There’s a relationship with Leonidas…and…well, we’ll see where it all goes.”

Awesome! This story will be less “THIS IS SPARTA” with a boot to the sternum, and more “I table the notion that the following may be identified as Sparta…. all in favour?”

Why does this not drive me into a mad frenzy of geeky devotion?

There was very little politics in 300, and we liked it that way. Now they are giving us a peek at the father of democracy and a man aspiring to be a god.

I say stick with the man aspiring to be a god angle and go with that. I hear he adds to his army of every nation he defeats, so there at least implies we might see some overly stylized combat scenes!