I haven't seen any in the U.K. I think it is too early in the process for them to generate any meaningful data. I do know there's been a bit of controversy, because it's actually created some fairly long lines at Heathrow Airport, which is known for its long lines anyway. I know that, to this point, the government is still planning on sticking with it, confident that ultimately they'll work out some of the kinks in the process and that it will add that element of security they're looking for.
On March 6th, 2012. See this statement in context.