AT&T in US has start to offer free WiFi access again for its iPhone users (some sites reported that it include all smartphone users). Once you connected to a supported wireless hotspot, for example starbuck, you can submit the form to receive an access link via sms. You will be able to use the link for the next 24 hours after activation. Once the link is expired you can go through the same process again to get another activation link.

See the full screenshot at slashgear here