Anyone hoping to see the Sony Ericsson X10 on T-Mobile, look away now or you'll be sorely disappointed. Phandroid noticed that the American version of the X10 won't support the necessary frequencies to connect to T-Mobile's network.
Yup, even though the specs page lists support for UMTS/HSPA 800/850/900/1700/1900/2100, Sony Ericsson is going to be localizing the radios. From the source:
UMTS HSPA 800/850/1900 only available for phones sold in Americas (except Brazil) and Australia. UMTS HSPA 900/1700 not available for phones sold in Americas. UMTS HSPA 1900/2100 available worldwide.
So that means you'll still be able to find an X10 that works on T-Mobile, just not in this country. You'll still be able to import if you want to use your expensive handset with T-Mo's cheap Even More Plus plans.
This also doesn't mean that the X10 is definitely coming to AT&T. Sony Ericsson wants to have a carrier relationship, but it depends on if one works out. As it stands, if anyone will be subsidizing that huge $880 cost, it'll be AT&T. [Phandroid via Engadget]