I experienced a "test" implementation first hand about 3 weeks ago. I was traveling on business from Miami to a South American country. While waiting for the flight, they came on the intercom and announce that all passengers would be subjected to a biometric scan. They setup (what I believe to be) a retinal scanner, and all the sheep lined up with no complaints!!
Except for me that is. I asked for the lead cop (TSA was not involved as far as I could tell) and informed her that I WOULD NOT COMPLY with this intrusive search. I informed her that I had already been cleared though security, had a valid passport, visa, and airline boarding pass.
She asked me why, and I told her that I was uncomfortable with the procedure, and that as a veteran (veteran's day was approaching), I disagree with this level of intrusion into my fourth amendment privacy. She asked me what specifically I had a problem with (since they "said" that the information would be deleted after 14 days), she went on to ask me why I was not concerned about people leaving the country. I told her that I found it ironic that they were going to this extent for people LEAVING the country, but could care less about those ARRIVING. She didn't appreciate that comment. Anyway, I was subjected to a separate "interview" with one of the cops. They asked questions that I are typical when entering a country, so I answer the questions politely. Lastly, I asked if he was a veteran, and he replied he was not, but pointed to another cop who was "guarding" the jetway. I went over and shook his hand and thanked him for his service (in an attempt to shame him for his actions). He did feel shamed, because he then said to me as I was walking away, that "you should be careful". I stopped and turned back to him and said "yes, and you should be careful too. You see there are many more of US good guys than THOSE bad guys." He had nothing to say, and I went on my way.