T-Mo use the same Frequencies as Wind, don't they? Or am I wrong.
Beamed over the interwebz from my iPhone 4 on iOS 5 GM
More accurately, WIND uses the same frequencies as T-Mobile USA, but yes. Most of the world does not use 850/1900, though. In fact, most of the world uses 900/1800/2100. T-Mobile's frequencies were carved out of 1800/2100. Only in the Americas is 850/1900 used. In Hong Kong and Australia, they use 850/2100, though.
The true reason for T-Mobile not getting the iPhone this year is probably because Apple forces each carrier to buy iPhones for multiple years regardless of how well they sell in carrier shops. For example, AT&T was forced to buy four years worth of iPhones at a supply level equal to half of their subscriber base at the end of 2007. In 2007, Cingular had 90 million subscribers, so Cingular had to commit to 45 million iPhones. Verizon did the same thing, though theirs did not have an exclusivity contract, so they just committed to 55 million iPhones for four years. Sprint had to commit to 25 million iPhones for four years (valued at $20 billion). If T-Mobile were to commit to the iPhone at this time, it would cost them roughly $10-12 billion. That money is better spent completing the nationwide upgrade of the home network to HSPA+ and preparing migrate GSM+EDGE to LTE.
Plus, if AT&T does acquire T-Mobile USA, then T-Mobile doesn't need to get the iPhone separately from Apple. However, if they do remain separate, you can bet Deutsche Telekom and France Telecom will get T-Mobile USA the iPhone as soon as possible. They can't afford that kind of competitive disadvantage.