This user reports who he bought the iPhone 3g and was not allowed tu upgrade to the new 3gd model:

I purchased an iPhone on 4/25/09. I searched online for information related to the phone before purchasing and read an article about the possibility of an upgraded model coming out soon. So before I bought mine, I asked AT&T if there was a new model coming out and was told there was not, that it was just a software upgrade which would be available for the phone I was purchasing. I’ve been with AT&T for several years and was excited to upgrade to a top of the line phone. Within a week I had to fight with AT&T to exchange the phone because of defective speakers for talking on the thing. After being treated rudely in the local AT&T store where I bought the phone, and several calls to AT&T, the phone was exchanged and everything was fine. Then the new model came out in mid-June, approximately 45 days after I purchased mine for $200 and a 2-year contract, a new model comes out and mine drops in price to $99!!!!!! I contacted AT&T and was told that they didn’t know about the new model until it was released. I was given the number for Apple where I was told that I’m no different than any other owner who just happened to purchase the phone prior to the new model release, I just happened to buy it closer to the new model release date. I think it’s absurd of Apple to treat customers in this manner. I don’t care about the new model, I’ve read that the difference isn’t that big of a deal. But I’m infuriated that I asked about this and was told not to wait when I should have. A coworker was told the same thing 2 weeks prior to the release…luckily he had waited to decide on getting the phone so he got the new model. Verizon/Sprint is sounding better and better. It’s a matter of principle and I may just pay the fee to get rid of AT&T and Apple now rather than give them my monthly business for the next 22 months!!!!!!! I recall there being a similar issue when the first model was released a few years ago and customers received some money back, if I’m not mistaken.

Here is my opinion on this: If you buy an old model any base a contract on this particular model it is clear that you are not allowed for an upgrade to the new model. Ok, there is Apple’s secrecy about their release cycles but that is their companies policy which is known and accepted.

If you buy a new car and the car manufacturer comes out with a new model a few weeks later no one would think about a free upgrade. It is the same with the iPhone, if you want an upgrade buy a new phone. You will find an unlocked version on eBay very easy.