Witness the first mobile phone + wVoIP . This is a mobile phone with two radios, one for GSM and the other for Wi-Fi. So when you're in a Wi-Fi hotspot, you Skype. When not, you cell. It's brilliant.
The slight problem is that mobile operators are not going to like this too much. You see, it means that when people are at home especially, and also at work, and maybe at the coffee shop, they're not going to be paying for airtime.
But so what? The technology is so compelling that the public is going to be kicking and screaming until they get it. In case you're not up to speed yet, wireless VoIP is internet telephony that runs over a Wi-Fi style network. It's also know as wVoIP and Voice over Wireless LAN (VoWLAN... keep up the crazy acronym work, people).
Now so far Microsoft looks like it's doing very poorly in the mobile arena. But, they seem to be the leading OS for Wi-Fi enabled cell phones. And there's already a not insignificant number of Pocket PC style devices that are being used for wVoIP, even if they don't have cellular yet. And you should note that this first phone, jointly developed by Skype and some tiny manufacturer called i-mate, runs... Windows Mobile.
I certainly that Nokia et al get in gear on this one, no matter how unpopular it might seem with the operators. Because otherwise they might let microsoft out of the cage that it's been so cleverly manoeuvred into.