To frame the themes of this year’s powwow — which opened Monday afternoon with Michael Dell (DELL) and Amazon (AMZN) CEO Jeff Bezos (pictured right) — my colleague David Kirkpatrick asked participants what is the most exciting technology innovation of the last 12 months. The most popular answer: the iPhone. That probably doesn’t surprise you, but the interesting thing is how Apple’s (AAPL) iPhone and its seemingly simple user interface fits the trend of the best and latest technologies. As one Brainstorm participant, Mitel CEO Don Smith, says about the iPhone, the Nintendo Wii and other recent innovations: “The most exciting trend has been towards simplicity in many areas of technology. Simplicity is essential if our society is to reap the full potential of technology.”

This idea that simplicity is increasingly the key to success keeps coming up here at Brainstorm. In an interview with David K., Jeff Bezos said that as Amazon developed the Kindle, the electronic reader that came out last November, it set a simple goal: to improve upon the book. “It was an audacious goal bordering on arrogance,” he noted, adding that the book has remained so unchanged for 500 years that Gutenberg would recognize it today.

The Kindle would succeed, Bezos explained, only if “the container of the book gets out of the way. That’s not easy.” He mentioned that he once had a microwave oven that beeped every minute after cooking was done, until you opened the oven door. “I called it the self-important device” — and that’s what he didn’t want the Kindle to be.

Turns out, Amazon designed quite an elegant and unobtrusive machine. “It’s not easy to make a device that disappears,” Bezos said, sounding almost Steve Jobs-ian. I haven’t used a Kindle, yet. But after nasty supply shortages the first few months, I can get one — and just might. Keith Reinhard, the former CEO of advertising giant DDB, told me this morning that he bought one, not expecting to love it. But he loves it. “I’m reading five books at one time,” he told me. (Reinhard started in the ad business in 1962, but he knows how to multitask like a gen-Yer!)

Of course, globalization’s evolution — with ever-increasing focus on emerging markets — calls for simple solutions. Joost CEO Mike Volpi, who once headed strategy at Cisco (CSCO), says he thinks the most innovative new technology is One Laptop per Child. That is Nicholas Negroponte’s program to spread computers across the developing world. “There is not amazing new technology in this computer, but cutting-edge technologies and open-source computing are intelligently packaged together to provide incredible value to the world’s poorest children,” Volpi says.

Nick Negroponte is on stage next. Gotta run!