US Xperia support both T-Mobile and AT&T?

When the Sony Ericsson Xperia was announced, the specs originally mentioned rather unusual frequency coverage, for both the more common AT&T and the much less frequently used T-Mobile 3G. These specs disappeared the the Xperia website for a while, but now appears to have returned with a vengeance.

In the published specs for the US version the specifications now list:

UMTS tri-band
UMTS 850
UMTS 900
UMTS 1700
UMTS 1900
UMTS 2100

This has led to rife speculation in the usual forums that the Xperia will also launch on the T-Mobile network. While we have no confirmation on this, if the above is true and not an error by SE, it would at the very least mean US users have a real choice as to which GSM network to use, vs being always tied to AT&T.

See more on the Xperia website here.

Edit: As we have seen, even during this post, the specs come and go.  I emailed SE for confirmation and got this response:

Me:I have a question re the Xperia X1. Does it, as per your website specifications, feature UMTS on the 1700 band or is this incorrect information?

SE: The specs on the site are correct. Thanks.

Thats good enough for me.