I think Apple may have been very clever here. Most people (in the UK anyway) and on a 12 months contract. So with about 6 months (US) and 9 months (UK) until the product release, people will not renew their contract and just set it to a rolling contract they can get out of with only 1 months notice. This will then give a bigger demand to the iPhone at launch and improve their sales figures. My contact end in Octobare so that could be perfect!