O2 has announced that it will only offer iPhone 4 to current customers only on June 24 due to stock shortages. A statement on their website says...
iPhone 4 will only be available for existing O2 customers at launch
iPhone stock will be extremely limited in the UK at launch and not everybody who wants one will be able to get one straight away. We want to make sure that our existing customers get priority so until at least the end of July, only existing O2 customers will be able to get an iPhone 4 from us.
O2 will have the iPhone 4 available to customers in O2 shops and at Carphone Warehouse, Best Buy, Phones4U and Apple Stores across the UK, but if your not with O2 already then don't expect an upgrade.
iPhone 4 will not be available on the o2.co.uk online shop until at least the end of July.
You need to have been a customer at O2 since 24 May 2010 to qualify for an iPhone 4 at launch.
What if I'm not an existing O2 customer?
We'd love you to join O2, however we always try to give our existing customers priority. As soon as we are able to, we will offer iPhone 4 to everyone who wants one on O2.
This kind of makes it awkward for potential customers of the iPhone 4 who decided to hold of getting the SIM free versions hoping to get a new iPhone 4 on contract. Hopefully the other 4 networks will have something decent to offer on launch day.
Full details can be found here.