A raft of sci-fi-inspired gadgets and technologies are being announced this month, promising a future of 3-D television, super-smart phones and next-generation electronic tablets that wrap the features of a laptop and a digital book into one wafer-thin package.

If you think you've heard all this before, well, you have. Moviegoers were donning 3-D glasses in the 1950s, and legions of gee-whiz devices have come and gone, with little discernible improvement of the human condition.