Jaron Lanier is that rarest of rare birds — an uber-geek who is highly critical of the world created by the technology he helped to create. Now 52, he first came to prominence in the 1980s as a pioneer in the field of "virtual reality" — the development of computer-generated environments in which real people could interact. Ever since then, he has attracted the label of "visionary," not always a compliment in the computer business, where it denotes, as the New Yorker memorably put it, "a capacity for mercurial insight and a lack of practical job skills."