Amazon started selling Kindle for $399.

The wireless e-book reader is supposedly the most important thing Amazon has ever done said Jeff Bezos.
Kindle allows you to directly purchase electronic books and magazines. Currently more than 88,000 books are available. New New York Times best sellers cost only $9.99.

Kindle holds over 200 titles and Kindle does not use WiFi, but EVDO like cell phones. This way you can get access the Amazon ebook store from everywhere. The nice part is that the access to the EVDO network is free. Kindle has no monthly wireless bills, service plans, or commitments.
You can also access Wikipedia.org for free and email your Word documents and pictures (.JPG, .GIF, .BMP, .PNG) to Kindle.
More details and video demonstration of Kindle on Amazon.