For those who have iPhones, the first step is to jailbreak your iPhone. Here are some tutorials:
iClarified - Tutorials - iPhone
Once it is jailbroken, you need to buy and configure MyWi.
iClarified - iPhone - How to Turn Your iPhone Into a Wireless Hotspot Using MyWi
I am no expert on these things. Up until now I didn't have a reason to jailbreak my iPhone. Following the tutorials above I was able to turn my iPhone 3G into a wifi hotspot without too much trouble.
64GB Wifi iPad Owner
Too bad for the 3G guys, rumor is NETFLIX is configured to run only on a wifi connection. I could smell ATT having a hand in it to limit bandwidth usage.
For Netflix users, I have viewed 2 movies on my iPad tethered wirelessly to my jail broken iPhone with perfect audio and video on Netflix. Makes jail breaking worthwhile now.
The only problem I have with my jailbroken iPhone acting as a wireless hotspot is the fact that when you are using it, the battery drains faster than it can charge. If you don't have it charging, the battery is dead in less than 2 hours.
I have tried to jailbreak, but it fails. I have a iPhone 3G, with 3.1.3 and am on windows. Tried snow and it failed..... Hope something comes up, I would really like to have the tether option.
iPad 1st Gen 16G
All 3GS users, who's iPhone has been built after week 45 DON'T upgrade to 3.1.3 w/o using proper unlocking tools. Otherwise you brick the phone and stay on AT$T for a while....
Look for Sn0wbreeze. This only works on Windows.
Most likely written on my iPad