O2 on their Twitter profile announced limited stock of the iPhone 4 for their upcoming launch. To conserve stock O2 has decided to keep the launch exclusive to existing customers until July 31st. This will most likely upset several newcomers but as some advice they can check out the other 6 carriers. Also, they can even blow their piggy bank on an unlocked version so they could use it on any carrier at any time. Now that’s what we call Carrier-hopping.