The promo video is very cute. It tells more about what Twitter already is than it does about their website’s new UI.
And speaking of the new UI, the unconventional design of Twitter’s new iPad app now makes a bit more sense. But it looks as if there are two significant advantages Twitter’s website has over their iPad app: (a) selected tweets don’t stay ‘pinned’ in your current timeline view; and (b) side-loaded pages are closable.