Our friends over at Wired had an article that attempts to answer the question.
- Creativity - "We have heard a lot about the econo-cratic Davos Man, but TED Person is a human mosaic of scientist, businessperson, design consultant and movie star. The spa and the laboratory sometimes clash. One of the most extreme reactions I’ve ever heard from the TED crowd was during a video shown Thursday where a cute little mouse was nosing around a piece of cheese. We hear a big SNAP, and the screen goes black. The auditorium erupts in a huge collective gasp of shock as we see our furry friend pinned in a mousetrap, pathetically struggling to get out. (All ends well, as it turned out to be a funny commercial and the mouse did a superhero move to escape.)"
- Construction of a personal narrative - "One contender for the best TED talk ever came a few TEDs ago when neuroscientist Jill Bolte Taylor’s described her near-fatal stroke — the professional part of her brain fluctuated between detached observation and panic while the rest of her mind melted into a blurry nirvana. The talk included candid revelation, medical peril, cutting-edge science, and a bit of mysticism. If she had included solar power and African child warriors, it would have been so perfect a TED talk that there would have been no need for others."
- Avoiding overused conventions - "[Stephen] Wolfram thankfully avoids two overused conventions of TED-speak. The first is the reference to 'the people in this room,' with the word people often preceded by an adjective like 'brilliant,' 'generous' or 'innovative.' Behind the flattery is a pitch to tap the brains and bucks of TEDsters for a cause, ranging from climate change to clean needle exchanges."