Gear Diary has an illuminating, alarming post about the DRM for Amazon’s Kindle e-books:
“How do I find out how many times I can download any given book?” I asked. He replied, “I don’t think you can. That’s entirely up to the publisher and I don’t think we always know.”
I pressed — “You mean when you go to buy the book it doesn’t say ‘this book can be downloaded this number of times’ even though that limitation is there?” To which he replied, “No, I’m very sorry it doesn’t.”
For what it’s worth, I’ve read Kindle books on three Kindles and two iPhones to date, and have never run into any DRM snafus.