So, the preview for the Skill Challenge chapter of the DMG II is up here and careful readers may note a reason I’m particularly curious to see it.
The skill challenge they present is, by the by, also a decent illustration of how to do a seamless skill challenge. While the DM can absolutely explicitly lay out the terms of the skill challenge so the players can play towards that, it also works perfectly well for “Ok, it’s the first day of negotiations: what do you want to do with the day?”. Player actions can just feed into the challenge appropriately, but the explicit tests in the challenge description provide fodder for suggestions to players looking for ideas, for for events that might occur and to provide guidelines for the DM for interpreting unexpected actions. Obviously, the desirability of keeping the entire challenge “behind the curtain” depends upon the group, I always like to have the option.