yeah, I'm thinking about to use a sh920 or one of the 905is in the US. it will be really cool, iphone is cool too, but i already got iphone touch, no fun to something similar. It seems the only reliable company is T-Mobile, but u know how their signal sucks, probably it only works in LA. Also, T-Mobile doesn't have its own signal tower, I am pretty sure they are renting from previous cingular, however, they are the only provider for 850 frequency, and att is 900 &1900 &3G. so it's not a good time to use any sharp and docomo phone in the states right now. I heard some time of this year, Verizon will open access to any carrier to their services, that means Jap phones may work under their services and I doubt verizon is the most reliable mobile company in the states so far. trust me... If you really want to use a jap phone like i do, you can get a canadian Fido or Rouge sim card, they work on 905i for sure, very few run out on 920sh. you can check it out on yourkbbs.com
otherwise use t-mobile or att within area covered by 1900.
good luck