The AP has an article about the possiblity of WiFi becoming the next big thing in mobile phones. The benefit is that with the increasing number of free "hot spots", calls and data could cost nothing (as long as you're in range of a hot spot).
Mobile phone maker Motorola Inc. plans to introduce a device that would seamlessly switch calls from cellular networks to cheaper Wi-Fi networks wherever they're available. Discount carrier IDT Corp. is testing consumer Wi-Fi phone service in Newark, N.J.