please say the iphone will work

It should. I'm on STX and all is good.

Ask the sales people or manager of the AT&T store for a map of where the towers are.

mine works just as well here on STT as it did on the mainland. No need to change anything plan wise except getting a local number as most places will not dial "long distance".

AT&T service (iPhone) works great on STT. On STJ, it will work great in Cruz Bay and most surrounding areas; there are many dead spots, though. Also, there was an article in the Source just today about how awful AT&T service has been lately on the Coral Bay side. http://stjohnsource.com/content/news/local-news/2010/03/09/att-cell-phone-service-terrible-coral-bay-residents-say

thanks everyone for the input!

the iphone will work

The only problem that might occur with a I Phone is if you need service /repair where will you get it done. In the states you must take it to a Mac store not AT&T.
That said, I think I get better reception with my I Phone.