KDDI R&D Labs have developed a software only motion sensor function for their BREW driven OS handset fleet. Early motion-capable models, such as the V603SH for Vodafone by Sharp, required additional on-board hardware to calculate spatial information in order to perform operations simply by moving the handset up, down, left or right. According to the company statement potential applications include menu navigation, gaming and enhanced location mapping services.
The clear advantage is two-fold. Since the system requires only a camera on-board to enable recognition (no additional hardware req.) and as a BREW application it therefore has the potential to run on a wide range of handsets already deployed on the street. This area has certaily has interesting potential going forward. .PDF (in Japanese) Here.