http://www.ifixit.com/Teardown/Kindle-2/624/1
Detailed walk through with pictures on how to open and disassemble the Kindle 2. The battery is fairly easily replaceable.
http://blog.fsck.com/2009/03/tethering-your-kindle.html
I think this was the original "tether your kindle via usbnetworking" post. The same fella also hacked his Kindle to get Ubuntu running (more or less) on it.