Now, I don't have an iPhone :( but I have changed my user agent to mimic the iPhone and done a few searches on there. It appears that the UK version isn't doing any geo-targeting (but this might be because I'm not really using an iPhone so it can't work out where I am).
I searched for [ebay] (and a few other major brands) on the UK version of iPhone Google and the results were all related to the US websites (unlike the results under most mobile versions of Google).
Localisation is even more important than normal with mobile search, so this surprised me a little. Does anyone have a UK iPhone? Can you verify my results?