"300" is one of them "phenom" movies that was absolutely huge for a moment in time and now feels like kind of a weird "why exactly were we all so hot for this?" footnote, so I'm not sure what kind of audience is waiting for a sequel. But they went and made one anyway, and now it has a trailer.
The actual plot of this one hasn't been widely disseminated (largely because, again, nobody really seems to care) but from what has been said and from what this trailer reveals (new additions include boats and the color blue) it's likely that they're attempting a larger focus than the tightly-contained original; likely focusing both on the battles of Artemesium and Salamis (naval engagements taking place during and after Thermopylae from the first movie) and apparently also the Battle of Marathon.
Rodrigo Santoro is back as Xerxes (the film will also feature extended flashbacks to the God-King's origin story) as are Lena Heady, David Wenham and Andrew Tiernan as Ephialtes. Our principal New Hotness is Eva Green as Queen Artemisia, commander of the Persian-allied naval forces.