Thanks for the feedback. I wonder why micro-sims are so hard to come by? I think both Viettell and Vinafone sell the iPad now, so it seems to me they should be able to furnish a visitor with a micro-sim card. When I went to Thailand last February, DTAC gave me a sim that worked very well. Even out in the countryside and many floors underground (in the subway) DTAC has a strong 3G signal.
I'm happy to report that it works in Vietnam too. A micro SIM card does not come easily in HCMC (Saigon) but these guys are just real savvy. They all have SIM card punches! We got ours from a mobile store just outside of Ben Thanh Market. She re-cut a standard SIM for us, used her earring to pop open the slot and voila! Worked right off the bat. I don't have the exact address but here's what I got....the store has a sign reading 'SIM CARDS' and it is located on the north side of Le Thanh Ton, between Nguyen Trung Truc and Thu Khoa Huan streets.