For a field that thrives on breakneck innovation, the personal-computer industry has not come up with a lot of fresh ideas of late. Since the introduction of the desktop computer in 1977, the laptop computer in 1983 and the Macintosh in 1984, there have been quite a few additional improvements but precious little that has been truly new and different. Progress, as they say in the business, has been evolutionary, not revolutionary.
That is why a product introduction scheduled to take place this week in San Francisco has sparked so much interest. After nearly 3 1/2 years of top-secret development, a...