Ebook readers have been around for over a decade. I remember attending a Book Festival here in Seattle, and seeing several booths featuring ebook readers. I was vaguely interested, but I am old-fashioned and I do like my paper. So, I never went any further toward learning more about them.
The latest entrant into the ebook reader market is Amazon, the Internet King of Books. Amazon's reader is called the Kindle, and it's quite nice to look at. They've chosen white for its case colour and it looks, to me, very retro-futuristic, a la 2001 or Minority Report. You can buy books for it, or even magazines and newspapers (the New York Times sans the newsprint marks on your fingers). It features an internet link, allowing for remote purchases. Say you're at Starbucks, hanging out and you just finished a great book and want another right away. Well, Kindle will get you one.
I think it's expensive. It's about $400, and that's before buying any books. Still, if you like to read books on the go and can tolerate the interface, it might save you money (and will certainly save you space) in the long run.