We have just had confirmation. Orange will offer the purchase of a 3G iPhone to those already owning the first model.
We do not know the details yet of this offer, but it will be revealed at the time of the launch of the 3G iPhone in July.
Note: it will only be accessible to those who bought an iPhone at the full price. This offer will not be available for those who bought a discounted iPhone, well, at least not initially.
[translation by crispin]