Just in case you missed it: Amazon last week announced Kindle. This is an e-book that, like the Sony Reader before it, uses an "e-ink" that is a lot easier to read than any other screen you've ever encountered. I've seen one of these in person and found 98.42% as easy to read as a piece of paper or a regular book. (I can't tell you how I reached that figure. It's proprietary information.)
What's different about Kindle is that it has built-in Wireless and that Amazon is making the wireless access free. This means that you can buy books wherever you might happen to be. Oh, and surf the web. And listen to mp3s. And read your favorite blogs (RSS subscriptions cost a small amount.) And favorite newspapers (New York Times delivery and others start at $14/month.)
There are all sorts of places where you can read about the $400 machine (a bit overpriced and more than a bit ugly [it's obviously not an Apple product]) including Amazon's own web page, which includes a video of Toni Morrison talking about it. But a good one that you might not find otherwise is at Macworld.
If I had more money, I'd get this. As it is, I'm waiting for the prices to come down. And for them to try to implement easier PDF support. Life would be much better if I could read journal articles on this. Did I mention that you can make notes on the things you're reading?