"Yes. My SoftBank iPad 3G worked just fine in the U.S. with an AT&T iPad SIM card during my trip this summer, even before I exchanged the iPad because of a dead pixel.
AT&T sells the iPad SIM cards for just $5. I slipped it in and it worked…"
"I'm skeptical because the iPad + 3G I have is actually one I got in the U.S. That is, I bought mine originally in Japan at Apple Store Ginza. But during my summer trip there was a problem, so changed it for one at an Apple Store in Boston. So…"