Remember when people dismissed the iPad as a fad? It's just a big iPod Touch, they said. Who would want one of those? Quite a lot of folks, actually. The iPad touched off a revolution that has grown to truly epic proportions. 207 million tablets shipped last year, according to market research firm Gartner, and that total is expected to grow to 256 million in 2014. The following year, Gartner projects that tablet shipments will hit 321 million units and eclipse PCs for the first time.