Just a quick note for Amazon Kindle fans on Windows Phone 8, the bugs in the recently released update which crashed the application if you upgraded the code from the WP7 version has been fixed, and a new version of Kindle is in the Windows Store.
The temporary fix (to remove the Windows Phone 7.x Kindle app before installing the new version) will no longer be needed, so users can just go for the upgrade. There's no pressing need to update the app if you've already installed it, but the Windows Store likes to keep you on the latest version, so there's no harm in grabbing it from the Windows Store.