
Barnes & Noble formally unveiled "Nook" today, its "dual-screen" eReader. There are lots of images and videos floating around provided by B&N. Here's a video demo (also on the Nook site). It's $260, essentially same price as the Kindle 2 and has more features. Among them it offers WiFi and a touchscreen, with color at the bottom.
This may not be the ultimate expression of the eReader, but it improves upon Kindle and immediately steals the buzz from Amazon's device -- a feat that so far no one has been able to do in the smartphone market vis-a-vis the iPhone. Here's the Nook-Kindle side-by-side comparison:

How will Amazon respond?
See also: eReader Market Kicking into High Gear