i too have t-mobile usa (nyc) i've had success getting the card to recognize since the first release but no luck making calls.
under settings -> general -> about
network = tmobile
carrier = (null) (null)

i don't know the version of my sim i faded away from reinserting it tooo many times :(

p.s i have another sim card from digicel (haiti) it works just fine, it roams on the att network here in the us
if i put my t-mobile sim after getting it to work with the digicel sim my carrier changes to carrier = carrier (null)

ok so i tried all that have gotten the sim to recognize and i get full signal, but when i go to general about
my network is tmobile and carrier shows up as (null) (null).

any ideas??