The filing for an “Integrated visual notification system in an accessory device” details an accessory that would act as an alert device as well as a traditional screen protector. The accessory would share design principles with current Smart Covers, so they could still be used to stand the iPad up, but also incorporate illumination elements like LEDs or simply utilise translucent portions, which would allow light from the iPad’s display to shine through.
Both the active and passive cover types are designed to alert users using shapes, symbols or words. The active form would output an illuminated notification visible to the user, while the passive format would light up a portion of the screen depending on its importance and type of notification.
This does seem like a useful feature, especially if you carry your iPad around all the time and want to keep up with notifications without waking the iPad all the time. However, it could also be quite a battery drain.
Apple has experimented with variations of the Smart Cover in the past, but none of the advancements have made it to market. Naturally, it is unknown when this particular product might be made available.