Like the six-string guitar, the mouse has remained pretty consistent since its mainstream debut in the early 1980s. Even high-end mice in 2010 follow the same conventions perfected at Xerox PARC: a device that lets users move a pointer around, and buttons that you interact with whatever has your interest. While the technology has made the mouse more effective as a computing must-have, the same basic principles still apply.
But companies, researchers, and concept designers are always eager to reinvent the wheel, sometimes as a creative exercise, or out of a genuine desire for improvement. Many times the results are pretty surprising, and even better, really useful.