An HTC-branded
GSM Touch should work fine in the USA, using either Tmobile or AT&T. Although it is officially tri-band, it has been verified to be actually quad-band.
EDGE data should work also.
But you may wish to wait for the Sprint Touch, debuting in early November. It will be a better device than the
GSM Touch, with faster CPU, more memory and
3G/
EVDO data -- provided you're okay with service on Sprint...