No; T-Mobile's US 3G data network uses the 1700/2100 MHz band, which currently available versions of the SGS2 do not support. So your data traffic would be limited to EDGE or WiFi.
You'll have to wait for a T-Mobile compatible version of the SGS2, which may or may not be coming. As far as I know, Samsung hasn't made any definitive announcement of one, but there have been rumors.