AT&T has just entered into an agreement with The Cloud, owned by BSkyB, for its customers to be able to make use of 16,000 WiFi hotspots throughout the UK. This means AT&T customers who frequently travel to the UK will be able to connect to The Cloud's hotspots and use up to 1GB of data without incurring any roaming charges or data overages. According to The Next Web AT&T customers will be able to subscribe to a data add-on, which doesn't necessarily make it free, but will prevent large data overages.
If you already have a data plan in place, which most users do considering the use of an iPhone or other smartphone requires it, you won't incur any charges you already aren't use to seeing on your monthly bill.
The Cloud is one of the UK's largest WiFi hotspot providers and continues to add more coverage across the UK. Make sure you download the AT&T WiFi International app from either the App Store or Google Play before traveling. This will allow you to take advantage of your 1GB of free data through The Cloud once you're abroad.
Source: The Next Web