Go out and order yourself a new iPhone 4 - chances are you'll be offered unlimited data. Except of course, you'll not be offered unlimited data. Confused? So is the UK Advertising Standards Authority, which is why the body is investigating the offers.According to MacWorld, the ASA is to review contentious terms such as ‘unlimited’ when it comes to marketing data. Right now, the term indicates that the company imposes no formal limit on downloading but reserves the right to limit a customer deemed to be breaching a 'fair usage' policy. But if there's a 'fair usage' limit, then it's not exactly unlimited.Some companies (O2 for example) have already changed their wording, becoming more upfront with data limits, specifically in relation to the iPhone 4 launch. Whether that's enough to please the authorities isn't clear. For now, the ASA will consulting with the British Code of Advertising Practice (BCAP)and Committee of Advertising Practice (CAP), both of which can introduce legislation on the matter. If they see the word 'unlimited' as misleading, expect to see it banned by the regulators very quickly.What will it mean to you, the mobile user? Well, that all depends on how much data you use. If you happen to be in the small percentage that hammers data, you'll soon be hammer in the pocket for it. But if your use is fairly average, the current price of your data deal is unlikely to jump up too much, if at all. Or in other words, you'll be paying for what you use.