As above this has been answered numerous times.
In fact I think this is now the 3rd thread I've read on the subject.
Orange UK are not allowing customer's to switch to a MicroSIM.
This information has come from numerous calls to 150, speaking to the Upgrades team, the iPhone Team, the Sales Team, and three friends who work in the call centre.
I'm starting to think that even the networks didn't realise that Apple were going to do this today, and so even they were unprepared for the revelation of the SIM Free, unlocked handset for Pre-order and everything else we've learnt last minute.
I'd imagine that all the networks are now in the process of arranging a setup to suit all of these customer's of there.
I got a pre-order (in store pickup) done this morning, and I am now very concerned that if things don't change I'm going to end up with a £600 iPot Touch (albeit with camera and high-res screen) and I'm not too happy about it.
As it stands today it looks like everyone who pre-ordered is going to end up on O2 (who will give you a MicroSIM) or they're gonna be hacking away at their existing SIM cards.
I for one, am very unimpressed with this.
Still if the rumours are true, we should start hearing from the networks in the next couple of hours of so (or maybe tomorrow)