A new study contends that Wi-Fi will expand faster in Europe because of Europe's cafe culture: I think there's a chance that Wi-Fi will grow faster in Europe but that's a silly reason why. There are plenty of places in the United States--take Seattle--that have very robust cafe cultures.
If Wi-Fi takes off faster in Europe it will be because operators there are sometimes more sensible then operators here. Already I'm seeing tons of roaming agreements in Europe which will make it easier for Wi-Fi users to get on networks. Here, those agreements are just starting to happen, and there are still some significant holdouts, like T-Mobile.
But this study makes one good point. Laptop penetration isn't as great in Europe as it is in the United States, meaning Europe is primed for an uptake in Wi-Fi enabled laptops. It could take longer for Wi-Fi laptops to replace those without here because so many people already have laptops.