Zarathustran: You pretty much nailed it. Dawnforge is more about putting the PCs centerstage and letting them create legends than about uncovering or retelling the legends of a past age. There will be rules for creating artifacts -- though it won't simply be a matter of spending a ridiculous amount of gold and XP. It'll require epic deeds worthy of the legends that will surround the artifact in ages to come. The setting will allow you to play kings of men, elf lords, and all the other heroic archetypes of a mythic age.
As far as dungeons, while the first great empires are reaching their peak in Dawnforge, they're still often built on the ruins of more primitive, precursor civilizations. So, for example, a great realm might be flowering in a particular region, but it's still dotted with the hill forts and barrow rings of the first barbarian kings to migrate into the area centuries before. In other words, there will still be dungeons! And finally, Dawnforge is set in an age of imperialism when a new, untamed continent has just been opened to exploration and colonization. It's wild, and unknown, and dangerous, and the perfect setting for extended adventure campaigns.
Nightfall: Continuing Z's analogy and using Tolkien as a convenient point of reference, Midnight is really an alternate Fourth Age setting (Sauron wins), while Dawnforge is a First/Second Age setting. They're both classic high fantasy, but the feel and play experience should be markedly different. In Dawnforge, you can create and play your own vision of Elrond. In Midnight, you play fugitive heroes in a world where the dark lord killed Elrond and made a fashionable dinner set with his bones.
Hopefully, the two settings will appeal enough to some folks that they'll want to play both. Others will no doubt find one far more appealing than the other. Variety, in my opinion, is always a good thing, and the d20 System makes it easier than ever before to take advantage of that (for both gamers and publishers!).
Thanks very much for the kind words and interest. I'm planning to post the one-pager in my Behind the Curtain column today, so make sure to check it out on our site:
www.fantasyflightgames.com