IBM has been awarded a patent for its new e-book device.

Patent 7107533 says :
An electronic book device runs at least two output mode threads-one graphics, and one audio-such that the device can both graphically display book content, and play the content over a speaker in the device. Annotations can be made audibly or graphically, and user commands can likewise be made audibly or graphically.
I don't know this move by IBM as what is so special about this device that IBM had to go for a patent?
Via: mobileread