I'm going to have to call T-Mobile about this - there is no reason why anyone would want to do this as SMS.
I can use Wireless Village all day long using only GPRS on my 6820 or K700i, and even a T630/T637 or Moto V600 and never once have to use a single SMS message.
I will be really annoyed if they are ditching TCP in favor of SMS of all things. I guess a way to test would be to talk on the phone while trying to send an IM to someone