But they are not forcing you to maintain a contract with them. If you find a 3rd party hack to remove the SIM lock, then you are perfectly within your rights to use that hack, and O2 will not attempt to take any action against you.
because that is against the SLA that you aggree to when activating your iPhone and voids your warranty.
another person says "why not contact apple?" well, you dont contact nokia for your unlock code, or sony erricson, you get it from your provider. the only difference is that for the iPhone there is no "code" the network provide your imei to apple, it gets placed on a database and will be unlocked the next time you sync with iTunes. i believe it also downloads an updated carrier file.
O2 in particular are using their "exclusivity" deal with apple as an excuse to refuse to unlock phones, even though they hold exclusive distribution rights to a number of other phones. the fact is, an exclusivity deal does not surpass common contract law where by a contract needs to be fair to both parties.
i believe that O2 are refusing point blank to send the imei numbers to apple,using the unlawful term in the contract and their "exclusivity" deal as excuses. they probably knew their deal with apple was ending a year or so ago, seeing as orange uk knew a year ago they got the iPhone, so O2 have spent the last year, and especially the remaining months before the market opens up to increase their market share and keep customers with them, which is fair enough, but they are doing it in unfair and unlawful ways.
this is all my opinion, and the opinion of someone in the legal field who is helping me out, but i reckon if it went as far as legal action, a judge could see it the consumers way