Despite his celebrity status, Bill Gates has never been known as a particularly dynamic public speaker. Toward the end of his tenure as a full-time Microsoft executive, Gates was called upon to give so many speeches that he would often lapse into long sections of uninspired boilerplate about "seamless computing," the "digital decade," or whatever buzz phrase encapsulated Microsoft's business strategy at the time.

That's apparently changing, based on the reaction to his speech last week at the TED conference about the future of energy and the potential for cutting carbon emissions to zero.

RealNetworks founder Rob Glaser gave Gates high praise in an interview with AllThingsD's Kara Swisher, and presentation guru Nancy Duarte says the Microsoft chairman's appearance at TED was remarkable, essentially redeeming him as a public speaker.

"Why is he suddenly a great communicator and presenter? What has driven his transformation?" Duarte asks in this blog post. "I think it’s because he moved from presenting about his job to presenting about his passion, and suddenly he communicates well."

Not to mention the fact that his PowerPoint slides have been given a major upgrade, to the point that they almost don't look like PowerPoint slides. Duarte has a series of images in her post, which is worth reading in full. Any presentation experts out there see any telltale clues of which software was used to make the slides?

I'm not sure I agree with Duarte's assessment of the reasons for the change. Gates was, without question, passionate about technology during his time at Microsoft. He was often at his best when speaking impromptu, particularly in small groups, about new concepts in computer science that were consuming his thoughts at the time. But that passion didn't always translate into his big public speeches, for some reason.

Maybe he has more time now to work with his speechwriters for big events. Maybe he's just becoming better at communicating his ideas. Or maybe he's secretly joined the Cupertino, Calif., chapter of Toastmasters International.

Whatever the reason, I'm looking forward to seeing a video replay of his TED speech, based on the reaction. It hasn't yet been posted to the TED site, but I'm planning to publish a follow-up post whenever it's made available.

Update: For the record, the slides were in fact, made in PowerPoint, according to a Gates representative. Some of the images were built in Photoshop and then incorporated into the slides.