These are getting more attention, not just on Flyer Talk, where they're referred to irreverently as Nude-o-scopes, but in publications like the New York Times and its Practical Traveler.
A few quotes that, ah, radiate from the Practical Traveler...
“This is all done to keep the traveling public safe,” said Nicholas Kimball, a T.S.A. spokesman. Maybe so, but there are still questions about how effective these machines are at achieving that goal.
Since there is no precedent for routinely screening so many people with X-rays — other than in prisons — there are a lot of unknowns.
...the machines passed a test developed, in part, by the companies that manufacture them and the government agency that wants to use them.
Since other passengers have said they weren’t given a choice, or were subjected to an aggressive pat down if they declined to be X-rayed, the Electronic Privacy Information Center has created an online form for travelers to report problems.
The article is worthwhile reading for anybody who travels, that is if you're concerned about either your health or your civil liberties... or both.