The other big tech headline Thursday was the release of Apple's iPhone software development kit and support for syncing e-mail and calendar functions on the device with Microsoft's Exchange Server. Kawasaki said the lack of that support previously is what caused him to choose a Motorola Q running Windows Mobile 6.

There has been speculation that Silverlight, Microsoft's new platform for online video and applications, could appear on the iPhone. I blogged about that on Wednesday. Ballmer was asked about it by an audience member. Here's what he said:

"Silverlight for iPhone is of course interesting. We want to do Silverlight everywhere. Now, I can't say there's been some extensive discussion with Guy [Kawasaki's] old boss [Apple CEO Steve Jobs] on this topic. And I noticed they just announced a new runtime today, yesterday. It sure seems they're trying to charge a whole lot more money for it than anybody else on the face of the planet. They want 30 percent of every bit of revenue that you collect on their runtime. It's a good business if you can make it. I'm not sure a lot of the software developers that I know are going to be very interested in that, but it may mean that Apple's not welcoming open, royalty free runtimes on its platform. We'll have to wait and see."

What phone does Ballmer use? He's constantly switching between various Windows Mobile devices, but lately he's been trying to simplify.

"I'm switching now," he said. "I'm having a hard time as I get a little older, I'm going back to a 10-key phone with a bigger keyboard so I can dial numbers, if you will, by Braille instead of dialing by looking."

Check out our complete coverage of Ballmer's Q&A with Guy Kawasaki.