Thanks for posting a link to the letter sundial. I flew to Seattle last Wednesday, was selected for the backscatter at O'Hare, and I opted out. Thus, I was patted down. The TSA woman was very respectful, asked about any sensitivities and explained every step before carrying it out; the process was tolerable. I requested fresh gloves, though.

What is most annoying about security in the US is how reactive the process is: shoes, underwear... I think having bomb sniffing dogs in security would be more effective than any X-ray or "enhanced pat down". Dogs would also be friendlier.