It seems T-mobile figured out the formula of getting more sales and new costumers, and with these new deals they might get more HD2 sales. The offer is only for participating T-mobile stores, but if you can find a store with this deal and some HD2 in stock here is what they require. One, an Iphone. That is all, if you have an Iphone and would like to upgrade to 1Ghz goodness, then this deal could help.
The deal does not pay for all the cost of your new HD2, it gives you store credit for your HD2 purchase. You can get as low as $100 credit and as much as $350, which if you remember is very close to the $450 HD2 price tag.
This could help people that need to save money, or cannot afford the HD2.