That teaser is up on Apple’s website right now, most are speculating that this means there will be some sort of cloud syncing solution. Which would negate people’s primary argument against the MacBook Airs, which is that they do not have adequate storage – if all your media is in the cloud then local storage becomes mostly irrelevant for 90% of users.
However, I am not sold on the cloud storage/syncing angle just yet. And I certainly hope that Apple doesn’t shove such a feature into the already bloated iTunes. Don’t get too wrapped up in the rumors from this today – nobody knows what this means aside from a select group at Apple, and they are not talking.