Depending upon where you're coming from and what model you intend to purchase be careful if you get a 3G model. In the US, as I'm sure you know, there are two models - Verizon, which is CDMA - and AT&T, which is GSM. Only the AT&T model works outside the US, CDMA is not supported anywhere else that I know of, not even Canada. Also, even the GSM models need to be initialised (i.e. data plan started up) in the US. If you don't do that you'll be unable to use it outside the US. If it's been initialised in the US the microSIMs from other countries will work just fine in it subsequently.