Geronimo-
Jag72 is correct on how it's done. In my case, I have my PDA phone on my belt all the time. Sometimes I will carry my ipad with me outside my home base wifi zone. So, when I do that and need to do something like access my desktop or just surf the net with a bigger screen, the ipad is what I use but to do that, All I need to do is open an app on my cell phone that activates a wifi hotspot from my belt cased PDA. It is secure with WPA encryption. Now I just launch any internet required app from the ipad. The ipad finds it and launches automatically. Not only is it a lower cost method than buying an ipad 3G and subscribing to AT&T, but it doesn't suffer the increased battery drain on my ipad like the 3G ipad does.
In fact, sometimes I need to use my laptop because it does some things my ipad can't do like file transfer protocols and maintain my webcasts on my server. I do the same thing with my laptop, tether the laptop to my cell phone. Would you say the same thing about my laptop?
Understand this- the ipad requires internet for some things and it's access is via wifi. Whether that access is via a router to my Cable company or from a public wifi hotspot, or from my cell phone router, it always requires some external service to get internet.
On my last trip I did I had to carry my laptop for only one purpose the ipad could not do. I had to download some files from the internet and print them on my portable inkjet printer. I also had to carry a Canon BJC-85 printer. No way to print from the ipad to that printer.
My laptop used to have it's own internal verizon 3G radio but that cost $59 per month for unlimited. I cancelled the account and now just tether the laptop. Lower cost and just as good. In fact better because now I can use wifi router to tether more than just the laptop to my cell phone.