It's safe to say the Kindle DX is now toast. Dollar for dollar, you get a whole lot more value from a bottom-of-the-line iPad. The regular Kindle is radically cheaper, so I expect it will continue to have a healthy market. I'm modestly curious how Apple's iBookstore may compete with the Kindle bookstore and app. If I got an iPad, I'd presumably install the Kindle app right away and then have all my existing books. Now, whether I'd buy my next book one way or another...
Were I to get an iPad, it would mostly live at home, near the TV, for "casual" use when I can't be bothered to go up to my office and use my "real" computer. I presently have an HP Mini 1000 running Ubuntu Netbook Remix serving that purpose. The iPad would presumably be nicer in some respects, and more annoying in others.
Anyway, I'm sitting this out for now. Maybe once somebody puts one in my hands and I have a chance to play with it, I'll think differently. Or, maybe if/when the novelty wears off and the Reality Distortion Field is gone, there will be a rash of these things on eBay.