@Artur yes it is the idea, using this screen to display information that doesn't need the... 'full display'.
Imagine this, you are in the public transportation, you could have a map displayed on this screen with your route, You wouldn't be forced to open your tablet.
Another example, you could read a book/document, but that would need some computing power and memory to be included.
Another possibility, you have the tablet in the docking, you close the cover and the display is used as clock (ok ok, a very expensive clock )
It's like an interactive cover.
The cover could contain a small battery and be linked to the tablet through low power bluetooth or wireless or connecte through the dock connector. The battery would be charged through the dock connector when you attached the keyboard to the tablet.