Given that Microsoft have just released Windows Mobile 7 and is still in process of spending 1 billion dollars to promote it and given that - according to several reports - Sony's next PSP is going to be touch sensitive, it is no wonder that both companies are researching and filing patents for all sources of improvements they can bring to touch-enabled handhelds.
Of note is Sony's latest patent filing which suggests having a touch panel mounted on the back of the handheld to act as a touch input for the display screen on the front in order to allow users to interact without obscuring portions of the screen with their fingers.
As for Microsoft, the Redmond giant has filed a patent for the use of ultraviolet light to create a "topography changing layer" which provides varying tactile feedback - such as "serving as a virtual button."
