The Department of Homeland Security announced that it was discontinuing its color-coded security advisory system today. In the software security world we often try to have big dashboards with red, yellow, and green indicating important things about our software. This is a great example of where such dashboards fail.
Facebook is savvy about time zones and the fact that its users span the globe. But notice this conversation I had with a friend. He sent it at 12:39am on October 21st. I replied 3 hours earlier. Now, if you look at our profiles, Roy and I live in the same time zone. Normally this would never happen. But, I happen to be in the UK when this happened. I think I replied a couple hours after his message, but at you'll see, it's essentially impossible to know, given what I see.