iPad users have a low resting heart rate...sitting, reclining, a device of leisure and recreation - and this should drive a lot of the design decisions.
Avoid "greedy pixel syndrome" - continue to recognize the value of white space. Don't just jam in the information. Let me ask for it when I need it. Create an environment of "ask and answer". Make each tap satisfying. Think: tap quality is more important than tap quantity.
Media hypertrophy / overkill - it's tempting to focus on first time use, but more important to consider people using them every day. Example: ABC news website has an awful globe thing showing all the videos - good for demos (perhaps), but a bad presentation of news, much of which can't be seen - and therefore poor for repeat usage.
Supress the urge to show off. Focus on the content more than the form. Example: Solar walk. Sophisticated interface, but it falls away so you can focus on the content. Example: Marvel comics, great example of how to get past the interface, get to the content. Example: New York Times - familiar isn't always bad.Example: Flipboard - comfort and familiarity. And people love it. We have centuries of know-how when it comes to presenting text - lean on it.
But don't be too tied to analogue - are page flips necessary? Feedback is good, but speed and feeling are critical. Don't distract.
Side note: iBooks enables page flips, but on iPad calendar / contacts, even though the information is shown in a book form, swipe to turn page doesn't work. Actually deletes contacts!
Ask: Is different actually better?
Avoid metaphor clutter. Choose one and make it work. If it looks like a physical object, people will try to interact with it. Example: App called "Manage" uses several real world metaphors that make you want to interact - but you can't.
Avoid popover pox. Example: Twitterific is great, but should just use popovers for quick peeks - not for extended exploration.
iPad elbow. "I hate the iPad's back button with the heat of a million suns" - too small, too high. Example: Twitter app does a great job getting rid of the back button. Think: Where do your fingers naturally come to rest?
We're so used to mouse pointers, but using fingers to touch changes things Psychologically, Ergonomically and Emotionally. "Big screens invite big gestures"
The old adage of the medium being the message is now turned on it's head. Now, "the message is the medium". "Buttons are a hack". 2 year olds have a fresh perspective on this.
Explore multitouch gestures. Example: Uzi draws you into experimentation. (From a chat I had with him afterwards: What affordances can you give to show multitouch gestures are available or enabled? For more conventional apps, you obviously need to avoid presenting multitouch options up front, as this would probably confuse the user as they're getting started. Maybe consider hiding them under 'help' settings, or showing a couple of circles flicking across the screen to hint at the functionality. Another option is waiting until say fifth time of use before being more explicit. And then perhaps repressing the hint when you'e detected that the function has actually been used - although remember that iPads, unlike iPhones, are often used by more than one person)