I have used an iPad for a while now. At home, in the office, up and down a few planes (tip: you do not have to take it out of the bag at security, which is nice), at conferences. My iPad is Wi-Fi only. It does not have the 3G option.
Many people have asked me if I will upgrade to the 3G version. My answer? Nope.
First of all, let me ask you this: do you have a smartphone? Do you have a data plan on it? If the answer is no, then it is a different story. But if you are an early adopter (and only early adopters get a device that has been released less then a month ago), you already have a smartphone with a data plan.
Now, the next question is: are you paying for your smartphone data plan? If the answer is no and your daddy is paying for it (or your company), then you might not care. But if you pay for it, what Apple is asking to do is to pay twice. It is $14.99/month for 250MB or $29.99/month for unlimited. On top of your data plan, which - if you have an iPhone on AT&T - is $30/month.
Granted, the iPad data plan is prepaid, so you do not have to buy it every month. You can decide not to pay when you are home and pay when you go on vacation. But does it make sense? Only an idiot goes on vacation with an iPad (guilty as charged :-) And when you taste 3G... you won't live without it, and you will pay every month.
Ok, let me ask another question: when do you think you are going to use the iPad with 3G? Not at home or in the office. Not at the coffee place (they have wi-fi). Not at the airport (same as before). Not on the plane (you have to turn it off anyway, and if they allow you to connect, that will be wi-fi).
So, when do you need 3G? When you walk down the street? With a thing that does not fit in your pocket?? Taking it out of your bag to check maps and walk around with the device in your hands (it is heavy after a while, even if it is light...)? Didn't you say you had a smartphone and you could do that with it?
Ok, I get it. On the train! Unless they have wi-fi, of course. And unless you are in the US (and you know how to drive :-))
Honestly, if you are like me and you have a smartphone, the need for 3G on the iPad is limited. In a month of use, I had the need only once: I was in an airport that charged a fortune for wi-fi, and my daughter really wanted to buy a stable on WeRule (very addictive online game...). I could have paid for wi-fi, though...
Or maybe one day I will need to buy a book online on the bus to the airport. Or on a cab. Or in a bar with no wi-fi. Or at the stadium (not where the Giants play, there is wi-fi there...).
My answer for these extreme cases? Tether it to your smartphone. It has 3G already, and you are paying for a data plan. Make them talk and you are good to go.
The issue is that the iPad has only wi-fi. So you need your smartphone to create a wi-fi hotspot the iPad can use, you connect to it and your phone bridges the network to 3G. BTW, this works also for your laptop, so it is an added benefit, in case you are traveling with your laptop and the iPad.
The problem is that the carriers do not like it... It sucks too much data off their network. They will prevent this from happening as much as they can.
What are your options? It depends on your device. In any case, using any of the solutions below means breaking the contract you have signed with your carrier... I am not giving you advice to do this, do it at your own risk and peril. If they catch you, they could make you pay or, most likely, shut you down.
iPhone: I use mywi. It works like a charm. It is $9.99 and it requires you to jailbreak your iPhone (I told you, AT&T does not like it). There are other ways to do it, but this is the simplest.
Android: you have to root your phone (same as jailbreaking for the iPhone), then get the Barnacle Wifi Tether app from the Market. Also, there are some mods that have tethering installed. One that I would like to try out, when I find some time to do it, is putting the HTC Sense UI on my Nexus One.
Symbian: I haven't tried it personally, but I am told that JoikuSpot works well.
Palm: WebOS is the only OS I know that allows you to do it legally, simply because Verizon is nice. Actually, they might just be desperate (Palm) or not believe they will sell many (Verizon), but since the beginning of April you can now get Mobile Hotspot for free (it was $40/month...). On Sprint, you are out of luck (sorry...) since they are pushing MiFi (see below).
BlackBerry: I looked around but I could not find anything. And my Curve does not even have wi-fi, so I cannot try it anyway... If you have a solution, feel free to add it in the comments.
Windows Mobile: I do not care anymore, I use mine only for demos. I am waiting for WinMo 7, so should you.
What if you do not want to root, jailbreak, or do anything illegal? You can always buy a MiFi from Sprint. It is free with rebates, but you still need a data plan... If you are not planning to tether your laptop as well (or your wife's iPad), you are back to square zero.
And, BTW, it is only for emergencies, so you can actually survive without tethering...