DreamWorks Animation CEO Jeffrey Katzenbereg loves his iPad.

Really.

Speaking this morning at the Wall Street Journal‘s All Things Digital confab in Southern California, he said that the iPad will be Steve Jobs’ greatest legacy.

Hard to fathom since Jobs, in the 34 years since starting Apple (AAPL), has revolutionized many industries: computers, movies, music, and phones.

Last night at D, Jobs declared the era of the PC–meaning the desktop and the laptop–over. “The laptop is yesterday’s news,” said the DreamWorks (DWA) boss today, agreeing.

Katzenberg agrees so wholeheartedly, in fact, that he said when he flew to Melbourne, Australia, recently, he didn’t take his usual bag bursting with newspapers and magazines and film scripts. He carried his multitudinous media digitally on his iPad.

He’s not using his laptop at all anymore, he added. His two media lifelines: His iPad and his BlackBerry (RIMM).

And although he’s a movie mogul with a vested interest in the big-screen mega-plex’s survival, Katzenberg believes that we will eventually consume more media on the 10-inch Apple touchscreen and its tablet ilk than on any other platform.

“We are going to see these devices in the hands of three- and four- and five-year olds,” he added.

My two cents is that this may not be so crazy. On Saturday, while buying a keyboard to attach to my iPad (for a mere $60), an Apple store salesman insisted that he knows a six-month-old baby who plays with an iPad.

And for what it’s worth, I wrote this Postcard on my iPad while sitting in the audience at D. The two attendees sitting next to me, Martha Stewart and tech guru Esther Dyson, are here multitasking on their iPads too.