Some things you just have to see in action to believe them.
Imagine you're cutting some wood on a tablesaw and your finger accidentally slips in front of the blade. Zap! No more finger, right?
If you're using the right tool, that spinning disk will stop before it slices through your delicate pinky. In fact, it probably will hardly scratch you.
Fine Woodworking has posted a video demonstrating this. The actual demonstration is near the end of the six minute video, so if you want to skip ahead over the boring (for some) details of the saw itself, go ahead.
To test the SawStop technology, they substituted a wiener for a finger. But it's very impressive anyway.
Here's the link to the Fine Woodworking video.
And here's a link to more videos on the SawStop site.