RIM recently filed a patent application showing a very interesting change to their basic Blackberry design. The patent talks about something called a “multi-tap keyboard user interface”. The intent appears to be adding auditory feedback when pressing keys to help visually impaired users.
The patent suggests that users will press a short series of keys to activate the multi-tap interface, and then use a pre-designated set of keys for typing out numbers or text. The user would be alerted via an audio queue what number or letter they have typed, and also be able to choose different menu choices while browsing their email. For all the details (such as they are) you can read the patent application yourself.