its weird,maybe tmobile is just launching it with just edge. i doubt cingular will pick up the n95 because they have the iphone coming out and wouldnt want it to bump heads with the n95 and lose money.
There are supposed to be reworked versions of the N90 and N95 that support quad band EDGE and AWS 3G. Possibly different model numbers at launch. Goes with T-Mo's new 3G network this year. Look at this in case it gets taken down later.
In any case, it's relatively easy to flash unbranded firmware onto these phones, and T-Mo should be able to unlock the phone for you if you're a customer.