Just got my nook today, finally, I must say is a beutiful piece of hardware, I don't really care about battery life, the openess of the device is what it matters.
Of course if you go for a Kindle 3 you probably wont regret either, is just a matter of what you prefer, be tied to Amazon or be tied but with a great range of choices with the nook.
BTW: did you see this comparison between K2 and K3? Interesting to see, anyway the screen of the nook is awesome
And I found the keyboard of the kindle awful.
http://kindleworld.blogspot.com/2010...of-screen.html