Update: Major correction here. User Jibiti at the Pixar Planet forums points to an IGN.com article published yesterday that contains some additional details regarding the event.
Saturday's presentation, it turns out, will be hosted by Eric Moro, Editor in Chief of IGN Movies. Also on stage will be WALL-E producer Jim Morris, who'll be introducing the footage. Some of the clips will indeed be brand new and never-before-seen –not the same as those shown at WonderCon.
I'm actually thinking of flying down to New York for this. Seriously. I've flown to NYC for day trips before as it's a pretty short flight from T.O., near where I live. Don't think I'll find any reasonably priced tickets this late in the game, though.
Plus, I hate comics... :)
(Update at 5:18 PM)