How many people own said Skype 3G device? How many people own cell phones? The point is, if you want to be making calls over the wireless network when you're out and about, chances are you won't be using a device capable of making unmetered Skype calls over 3G (at least not for very long, or with much success). You'll be using the carrier's sanctioned and costly services. You can make calls over 3G today with Skype on the iPhone, and it's free for now, but they say it'll only be free until the end of this year, and then they'll be charging for it.
The carriers are flexing their leverage over Apple/FaceTime and Skype to fight any free VoIP services on their networks. Look for a paid FaceTime-over-cell-data-network plan to emerge in short order, with revenues going straight to the carrier, along with Skype's.
http://blogs.skype.com/en/2010/05/iphone_calling_over_3g.htm...
The carriers are flexing their leverage over Apple/FaceTime and Skype to fight any free VoIP services on their networks. Look for a paid FaceTime-over-cell-data-network plan to emerge in short order, with revenues going straight to the carrier, along with Skype's.