I am of two minds concerning obstacle detection.
On the one hand, mobility specialists and people with vision impairments share a common desire that their tools be simple to use, reliable, and affortable. It makes sense then to make a device that does one job and does it well. The current state of technology makes it an easy task to create such tools, and there are a bunch of them on the market. Also, because they are so easily created with today's level of technology (much of it off-the-shelf; components available at Radio Shack, etc.) many people will discover "the next wonderful invention for blind mobility." From engineering students in graduate schools to backyard entrepreneurs, expect waves of "new obstacle detectors" for the blind. It should be possible now to custom make such systems to address the needs of blind consumers who want such tools.
Here is a list of past and present (primarily handheld) obstacle detectors:
The Lindsey Russel Pathsounder
The Mowat Sensor
The Pathfinder
The Miniguide
The Polaron
The Walkmate
The second half of this story is that technologies tend toward complexity. Vision substitution systems, for example, have obstacle detection and avoidance as a built-in feature. Wearable computer systems for the blind traveler also can have modules for obstacle detection. This is the direction that evolution is forcing us. When the cost factor for building and marketing an obstacle detection system is about the same as building and marketing a modular, multi-functional technology (that can be used by a broader range of consumers), the stand alone obstacle detection systems may fall by the wayside.
With ever increasing amounts of intelligence being built into our tools (and environment), it makes sense that we will see the cane evolve into a complex multi-functional electronic tool. This evolution is just beginning and will evolve as affortable technologies rapidly unfold. Here is a list of pioneering smart canes:
The Laser Cane (Nurion Industries, Pennsylvannia; no website)