Don't get me wrong! I welcome the iPad for a couple of reasons. First and foremost, if it gets people to read more books, it has to be a Good Thing. Second, maybe this will finally make Amazon toe the line and support the ePub format for ebooks? And in general, competition is not a bad thing for technology. However, as Penguin CEO John Makinson said recently, books themselves are likely to change. This could provide opportunity for publishers to expand their product lines, but it's also a case of be careful what you wish for. The bigger market the iPad will bring could attract newcomers with deep pockets, ready and willing to develop shiny new toys to separate consumers from their money. Traditional book publishers who try to compete could be left in the dust.
When digital cameras and color printers got affordable, people stopped buying film cameras. Kodak is still around, but they don't sell much film, and their competition in camera manufacturing includes the likes of HP, Cannon, and Samsung as well as Olympus and Leica.
Amazon is a retailer. Jeff Bezos would sell his grandmother, if he could figure out a cost-effective way to ship her. Assuming the Kindle for iPhone app works on the iPad, Apple could be Amazon's biggest benefactor. But if the iPad lives up to its promise to deliver a new world of book-like entertainment, publishers could well find themselves having a Kodak moment, and not in a good way.
Note: Here's a link to second video where the Penguin folks demo some "enhanced iPad ebooks."