Gruber was talking about this is his podcast and how, as good as the Retina display might be, you can't spend an hour talking about it. It's simply something you have to see in person. His suggestion was that Apple might introduce an iPad version of iPhoto or Aperture. That would be a good way of highlighting the Retina display but I'm not sure now an iPhoto app would fit with the control that the built in Photos app has.
High-end magazines where the quality of the presentation is a big part of what you're buying is another possibility. I thinking about National Geographic or the evo car magazine in the UK. Another possibility is that they spread the time between a bunch of other things like a new Apple TV or (from left-field) an Apple games controller add-on for Apple TV, iPhone and iPad.