The same is also true of physical barriers. While 4G has no trouble going through your home's walls, if your home office is in a basement or you live in an area with many tall office buildings between you and the closest 4G tower, you're going to see poorer performance.
In addition, not all 4G towers are created equal. If your local 4G tower, for example, isn't that tall, its range will be less -- even on the Great Plains. Some 4G locations don't have as much as bandwidth to share with users as others do. So, for example, one 4G hotspot may be overloaded with users all streaming Toy Story 3 while another company's 4G tower, with the same number of users doing the same thing, may be delivering the movie just fine because it has a much wider backbone pipe to the Internet and the content delivery networks (CDNs).
On top of this, none of the 4G networks are compatible with each other. So, for example, if you decide you've had enough of Sprint with its WiMAX network, you won't be able to use any of your 4G equipment with Verizon's LTE network. This also means that there's no such thing as 4G roaming. If you're not on your native 4G network, you're not going to get 4G even if you're looking right at a competitor's 4G tower across the street.
4G coverage and costs
The single most important thing that will determine what kind of 4G access you'll get though has nothing to do with technology and everything to do with business. Not only are the 4G networks and their hardware incompatible with each other, none of the 4G networks, despite any advertising you might see, have anything like broad, nationwide coverage right now.
So, before signing a contract with any 4G wireless carrier, make darn sure that they offer coverage in your area and any area where you frequently travel for business. To obtain this information, check on the coverage maps for each carrier (see sidebar for links).
I would also advise talking to friends, family, and coworkers who've already made the jump into 4G to see what their experiences have been like. As AT&T iPhone users know all too well, the mobile broadband providers can say all they want about their speed, but if they can't support all their users, or they don't have enough towers to deliver coverage in a given area, you'll still see poor performance.
You should also look carefully at just how much total bandwidth you get per month and if there are any restrictions at just how fast you can go at any given time. For example, T-Mobile recently proposed a 500 MB (MegaByte) per month cap on its service in the U.K, while Virgin Mobile restricts some users to using no more than 256Kbps (Kilobits per second) on its 3G network, which can reach up to 800Kbps.
In short, check the fine-print of your 4G deal. You might not be getting as much out of the network as you thought you were. Even high bandwidth caps, such as 1GB (GigaByte) per month may not be as high enough for you if you plan on streaming a lot of video or using videoconferencing. Indeed, as has been noted, it's not too hard to blow out a 5GB data limit if you watch HD video.
You should also keep a close eye on changes to your mobile provider's contracts. For example, AT&T got rid of its "all you can eat" plan in the summer of 2010 for new subscribers. As the mobile companies struggle with how to deliver the most 4G bandwidth to customers for the least amount of money, you can expect all the providers to make changes as they try to fine-tune 4G pricing.
4G and the last mile
At this time, I can see using a 4G smartphone. I can also see using a laptop or tablet that comes with either 4G built in or add 4G compatibility to it with a modem. If, that is, I live and work in the right place and the performance and costs looks reasonable.
I cannot, however, recommend using 4G for the last mile, unless your other choices are dial-up or other obsolete network connections. No matter what providers you have to choose from, the pricing and bandwidth caps are certain to change as we move into a 4G networked world. By 2012, things should be more stable and it will be easier to make a smart choice.