Maher Arar, a dual Canadian-Syrian citizen was arrested at a stopover in JFK in New York and deported to Syria by the US government. It seems to be unclear how they decided he was a "suspected terrorist" but it took close to a year in a prison in Syria and a lot of torture for them to decide that he was OK to be sent back to Canada. Obviously, it's probably easier for a Syrian national to get on a "list" than a Japanese, but this really scary. They say he had had a relationship with another suspected terrorist who is also being imprisoned and tortured now in Syria. He says he barely knew the guy.
So what does this mean for us? If we meet someone, we should not "become friendly" with them until we are certain that they are not a suspected terrorist. What does this mean? We need to make sure they don't hang out with other suspected terrorists. So if you believe in six degrees, it's likely at some point you will be a suspected terrorist.
How do they know if you hang out with someone? Friendster? LinkedIn? Your email? We need to be VERY careful about the privacy of not just the content of our communication, but the privacy of who we are in touch with, often called sigint, or signal intelligence.
Seriously though, this will cause a chilling effect on meeting, calling, emailing or otherwise "being in touch with" anyone who you don't know very well that could land you on the "suspected terrorist" list.