A fall when a bunch of people can suddenly sell is a normal thing.
And those insiders should sell parts of their positions. They are very heavily invested in FB and need to diversify, even if they believe FB is a very wise investment. Many insiders probably have more than 90% of their portfolio in FB stock.
All of this "giving away" of stuff has stopped our society from reinventing the wheel.
Unfortunately, the people "giving away" spend a lot of time reinventing fantastically-different but only-very-marginally-better wheels. Every week I see on HN about some new language or framework someone has invented that fragments the market even more. If you aren't being compensated in dollars, being compensated with being "the inventor of X" can come close, so there's a big supply of this.
"Missing stop signs" is one place where a google car would be great, since they pre-map the area and would know a stop sign has disappeared. Knowing that would cause them to slow down and be even more careful.
Autonomous cars never get distracted, have 360 degree vision, look at all things all the time, and can react in tens of milliseconds versus hundreds of milliseconds. I'd trust that over a "professional driver."
The people doing this have talked about how their autonomous car met another company's autonomous car. There didn't seem to be a problem.
Really, when there are more autonomous cars on the road, each and every one will get better from their neighbors. They can directly share the data they see and what they are doing. The network effects will be huge.
The 4-way stop was something they had to change from the ideal setup. The google car was obeying the law and waiting its turn and never getting it. They made it get more aggressive the longer it waits and now it gets through them just fine.