I was looking at this yesterday and so far all I have found is it's still unknown at this point what 3 UTMS bands it will support. Honestly, since the band IV (1700mhz Tmobile uses) UTMS is only used in North America, I really can't see them supporting this. One of the bands AT&T uses, band V, is also used in Australia and New Zealand, so that may be there, but once again I dont see band II as it's NA only. My guess would be bands I, III, and VIII, but maybe V instead of VIII.
Info on UTMS bands:
http://en.wikipedia.org/wiki/UMTS_frequency_bands