I think it's down the line and we need networks that can handle it, but I don't see why not. With VoIP, as soon as cities are fully covered this won't be too far behind. The biggest step is making cities wireless. I hear a year or so ago that they had trial products in D.C. or something that with one access point you could get wireless internet for miles.
Why dink around with VOIP when you can have the voice part covered by cell technology? Use the cell for voice and then whatever sort of ISP service the cell provider handles can be used for data. They already have uplink cables and dedicated PC Card devices that do this...why no just integrate the phone into the laptop?
City wide wireless only does you some good in the city. Lots of us are still rural, or at least have to travel through rural areas. I can get cell phone reception in many of these areas. I won't be able to pick up wireless.
I'd like to be able to pull over to a rest stop or the side of the road, flip open my laptop and dial up to check my email or do a quick mapquest without fumbling around with a PC card or a data cable from my Cell phone.