Unless you want to neuter any email, browser or data use of the iPhone, do NOT plan to use it outside the US!! Apple advertises the phone as providing "unlimited" data (email and browser) use at no extra charge once you are signed up with ATT. And Apple advertises the iPhone as appropriate for "international" use. Not so! ATT (which also says its plans include "unlimited" data use) will kill you with extra charges out of the country if you access email or the browser. Four days in Mexico netted me a $660 bill for only occasionally checking email and looking at a few news pages each day. ATT customer reps were rude and insulting ("you should have asked what charges would be leveled before traveling to Mexico!"--of course, there is nothing in the ATT promotional materials to indicate that there is any reason to inquire). After long conversations, an ATT supervisor reluctantly and imperiously "granted" a 50% discount for the outrageous ($20 per meg) data charges.
In short, don't use this thing abroad for any purpose other than as a simple cell phone!!!
Be warned!
BB
This is exactly the same with every other carrier and cell phone (Blackberrry global plans excluded). You'll run into the exact same customer service situation with any other company.
The iPhone is a PERFECT device for overseas. I just walk around with it in my pocket. Periodically it picks up open WiFi networks and fetches my mail for free. What could be better than that?