A few weeks ago I trekked to Anaheim and got to play with the new Earthlink WiFi phone as I went around the city.
In what is the first real WiFi VoIP project to be launched by any of the Muni WiFi providers the phone worked, much like a cell phone. Since its beta, I won't go through the minor problems which were found but also reportedly corrected.
The vision of Earthlink is to provide inexpensive VoIP service for those who don't need a cell phone. I view the combo in home, out of home service as the first step in a new era of portable phones.