The big corporations limit their locations that they accept Bitcoin until they're 100% sure about where they can and can't trade it, Overstock for example accepted it in the U.S and now they're moving to worldwide, it's all just because the laws are different in each country.
UK has more friendly approach towards bitcoin than US, but you can't pay with it on Dell.co.uk. I don't think uncertainty over regulations is a main reason. They're 'piloting bitcoin' to see how it works out, if it's worth the effort - they'll implement it worldwide.
Or maybe international divisions have enough independence to decide on such things themselves?