Last year AT&T opened up their national network of Wi-Fi hotspots so that iPhone users could have free access — Starbucks, McDonalds, airports, etc. But accessing these now-free hotspots was cumbersome, involving entering your phone number, receiving a text message, then clicking a link in that message. According to a great post on MacWorld, the iPhone 3.0 software makes this much easier. As soon as you're in the range of the network, the iPhone automatically switches to the network. The article observes that AT&T has a strong incentive to do this, since it's a lot better for them if your data is traveling the Internet rather their already-overloaded cell network.