>>http://europe.nokia.com/find-products/devices/nokia-808-pureview/specifications
>>http://betanews.com/2012/02/27/windows-phone-isnt-good-enough-for-41mp-nokia-808-pureview/
>
>What would be a practical benefit of having a camera with such high resolution?

No practical benefit. Much higher noise level, lower sensitivity, and far fewer pictures per GB. Most professionals will agree that 10-15 mega pixel gives you best total value.