I'm going to the U.S. in a couple of weeks and wanted to get a pre-paid sim card to use on my iPhone (it's unlocked) for the time that I'm there. The only problem is data. T-Mobile apparently doesn't offer data on pre-paid other than the Sidekick plan (that doesn't work on the iPhone anymore) so my only option is AT&T. I looked around and on AT&T's website there's a data add on for the GoPhone, $19.99 for 100MB. I've heard conflicting reports about this working on the iPhone. Does anyone know for sure? Is anybody using it?