Amazon has released a new update for Kindle 4 devices (version 4.1) and among other enhancements, the new software update will add a new Airplane Mode to your Kindle.
The new Airplane Mode will help you quickly turn off the Wi-Fi and 3G connectivity on your Kindle from one place.
Once you have applied the update, press the Menu button on your Kindle, select Settings and then choose Airplane Mode from the next screen. Once the mode is active, it will also add an airplane icon in the top menu of your Kindle screen (see screenshot above).
Kindle 4.1 also includes a new font that Amazon says is crispier and offers an improved paper-like reading experience. Head over to Amazon.com to download the new update.
It would download itself on your Kindle device over the next few days but if you want it right now, the Amazon website has the binary that you can transfer to your Kindle over USB and change choose Update your Kindle from the Settings menu.