No, they won't tell you it's optional, but it is. They cannot force you to go thru the xray backscatter scanner. The alternative is a "full hands" pat down, which I find just as intrusive, but I make it as awkward for them as they do for me. I will not participate, and I will be as obnoxious about it as I need to be. I have a real chip on my shoulder for the TSA and I hope they all choke to death on their bullshit. But ask me how I really feel.

Prior to 9-11, I used to fly from Orlando to Newark every Tuesday morning and return late that evening. I'd drive up to the airport an hour before my flight, walk directly to the gate, check in, and fly the 2 hours to Newark. After 9-11 it became a two hour ordeal. I understand the need for increased security, but air travel needs to return to taxi cab status, as far as I'm concerned. We can't live forever. :)