After several gaffes which saw the company prematurely activate and then pull the feature, AT&T has finally launched its free Wi-Fi access for iPhone users at all AT&T-branded hotspots in the U.S. The service will provide free high-speed Internet access to iPhone users at all AT&T hotspots, including those found at Starbucks. To access a hotspot, users must launch the Safari browser, enter their 10-digit phone number on the page provided,…