I always figured someday I may buy an unlocked iPhone, stick in my TMO SIM and be all set for phone calls, email (after setting up the iPhone to pull down my emails) and web surfing (using the TMO data plan, just like I occasionally do on my Curve) in the USA. E.g. I would surf with unlocked iPhone using TMO sim and the foreign carriers data network (the same network that delivers emails to me and lets me surf using my BB Curve).

Yes, I could also use the iPhone's WiFi (here and abroad) but always thought the TMO data plan (whether the US plan or the international plan) would also cover me. So, I figure, now (e.g. now that TMO has worked out the billing issue), since the TMO international plan is really just international email and not international data/web surfing (whether using my Curve or some other device), I would not want to be wildly surfing via a data network using my TMO SIM in an unlocked iPhone while abroad.