As a frequent International traveler who takes his Kindle everywhere, I have been asked several times if the Kindle can be used overseas. From personal experience, I can say that the Kindle has worked for me in South America and Japan. I have the Kindle DX model with the 6 inch screen, which is advertised as being usable in over 100 countries. I hope to be able to confirm functionality in all of the other countries listed in the future.
Using the Kindle overseas requires some planning. The user will want to make sure he has completed the registration process and linked a US credit card to his Amazon payment account. This will ensure that Amazon knows you are a US user.
While still in the US, I registered and prepared the device before the trip. The registration process and downloading of eBooks worked perfectly in the States. I even signed up for two magazine subscriptions.
In Colombia, the Kindle 3G worked perfectly; even though Colombia uses a cell phone frequency different from US frequencies. In Japan, I had been worried that the device would not work as Japan is famous for being the island where outside cell phones refuse to work. Travelers to Japan routinely find that their Worldwide GSM phones will not work. However, the Kindle DX worked just as well in Japan as it had in Colombia. » Read more: Travelling Worldwide With the Kindle