Here's my vote, anyhow:

Carbon spokes

From the article:
Coming around a corner, I felt a shimmy through the front of my bike. I straightened up out of the turn to bring the bike under control. A second or two later I catapulted over the handlebars. The rim of my front wheel had completely detached from the hub. I had not hit anything — not another rider, a curb or even a rock. I landed on my head and broke my shoulder.

The front wheel was Mavic's second generation, post-recall carbon-spoke R-Sys wheel.

[...]

In a steel-spoke wheel, at least four or five spokes must break before the wheel will crumple or taco. With the original R-Sys, it appeared that only one spoke needed to fail before the whole system came undone. Mavic contends that this problem was solved in the second-generation wheel.
 Well, err, notsomuch.

Check out the photos in the article of what was left of the wheel .