The cover, strongly reminiscent of Apple's current Smart Case, would be of a shape and size to match its host display, with a portion of the flexible material presenting visual information to the user. The size of this screen, and therefore the portion of the cover it would take up, is unclear, with the various images filed along with the application, hinting at a range of potential functionality.
The extra screen space could be used for a number of functions, including a media control interface, a notification center, a graphics tablet-like drawing space, or simply an area for additional, frequently used icons. The drawings also suggest other, more ambitious uses of the extra screen real-estate, including an attachable full-sized, touch-screen keyboard. This is strongly reminiscent of Microsoft's Touch Cover, an accessory for its upcoming Surface tablets. The application also states that the cover may feature “an electronic paper display requiring no power to maintain a current display state.” This is likely to utilize similar technology to the E Ink displays found on various eReaders including the Kindle range.
Like the current Smart Case, the device would attach magnetically to its iPad parent device, but this connection would act as a communication channel between the tablet and the cover, as well as providing power to the extra screen. It's unlikely that the accessory would be compatible with the current generation iPad, as one drawing details a four-pin connector on the side of the device which isn't present on current or past versions of the iPad.
If the device detailed in the patent ever sees the light of day, then it may well exhibit similar functionality to devices that feature dual touch-screens, such as Sony's P Series or Acer's Iconia Dual Screen tablets, albeit with a notably more versatile form factor.