AppleInsider reports today on a new iOS 6 feature that has been revealed in the latest beta, assuming it is still in the final version, of course. The new feature is called “Wi-Fi Plus Cellular” and can be found under General > Cellular systems setting. Basically, what the feature does is to help make it easier to use a Wi-Fi hotspot from your iPhone or iPad, by noticing when your Wi-Fi connection is breaking up and automatically switching you back to cellular data until the Wi-Fi connection is strong enough to use again. This should then ensure that if you are in the middle of syncing data or apps when your Wi-Fi signal fails, you will be able to carry on seamlessly (hopefully!) And if you don’t want it to do that, you can turn the function off via Settings. AppleInsider says that the feature will also try and keep your FaceTime video conferences from failing, but not for any devices earlier than an iPhone 4S, apparently.
Source: Apple's 'Wi-Fi Plus Cellular' option in iOS 6 to keep apps syncing when WiFi networks choke