Space Hoppers or Job Hoppers?

A few years ago, the ideal job was one where an employee could stay for their entire career, pick up a pension and then retire. For some people that is still the case, but the move to a more fluid employment market is now becoming the norm as we all know.
However, will we as recruiters in the UK, tolerate what is now acceptable in the US? What do I mean?  In the UK, employers(and recruiters for that matter) frown upon candidates that have moved job every 2 years (and less) and they get tagged as being job hoppers. However my experience of working in the US tells me that it is more acceptable to move jobs regularly,even every year, and that has also become acceptable with employers over there. They look on at as gathering experiences, therefore benefiting the hiring company and making them more rounded employees- I call them space (cv) hoppers!!
The question has to be………….how quickly will the UK employers start to adopt that ideal?