"Phft" says Amazon, makers of the Kindle. "Well ours lasts two months too!" From CNET:
...the product pages for the Kindle WiFi and Kindle 3G (along with their discounted Special Offers counterparts) have been updated with new battery life numbers. "Long battery life - Up to two months," reads the promotional copy.
So when released the Kindle 3 had up to one month battery life on a single charge, but now it's two? Did Amazon all of a sudden double the capacity of the Kindle battery?
Nope. It turns out all they did was halve the value for the amount of time they assumed one was reading per day. Specifically, only read for half an hour per day and turn off the WiFi radio, you'll get two months battery life. If you read for an hour a day, you're back to the one month battery life... A great example of an Argument by Artifice.