To the person who suggested that the Sony was thinner, you are half correct.
The PRS-505 is .3", while the PRS-700 is .4", Kindle 2 lands pretty much in the middle of those.
With regards to the battery, the handful of people saying there is a manual that talks about user replaceable battery, where is it? I just went through the Kindle 2 user guide and saw nothing about user replaceable battery (
http://s3.amazonaws.com/kindle/Kindle2_Users_Guide.pdf) just talks about charging.