For most users the changes aren't too troublesome (see http://en.wikipedia.org/wiki/British_and_American_keyboards) but I'm so used to coding on on the UK one I find it difficult to switch. The \, #, " and £ are the ones that cause my most difficulty. And to me, the little US enter key just strange (it's double-height on UK keyboards).
Yeah, I'm both a Linux user/enthusiast (I need `~\|# in the Right™ places) and a developer (Switched from DE to US mostly for []{};: etc - the UK difference would be smaller here: A moved \ and @" would be most annoying).
The tiny enter key is actually a requirement for me (to have \| in the right place). Hrm. So maybe I'll shoot one of these keyboards with the US layout on eBay in the future or something.
Now .. I can order it in various languages, the only English one being the UK layout. ;-)
I'm reasonably sure I want the US layout, trying to compare them now to spot the differences.
Edit: Yeah. http://en.wikipedia.org/wiki/British_and_American_keyboards - I am used to/want the US one. So still no luck unfortunately.