During the WWDC keynote, Steve Jobs boasted that 22 countries would be getting the iPhone simultaneously on July 11th: Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Hong Kong, Ireland, Italy, Japan, Mexico, Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland, UK and the US. Unfortunately, it appears that one of those countries is not like the other, and won’t quite be making the cut for that first round of availability.
As for why the 17th, Orange did not give a reason in its press release for the change, but perhaps it has something to do with the Bastille Day holiday on July 14th? Or perhaps they displeased Steve Jobs in some way that only the French can, like cutting off his daily source of croissants. Horreur!