TUAW How-To: Use iPhone 4 microSIM in a iPad 3G for Wireless Data

This how-to from TUAW (The Unofficial Apple Weblog) is not for everyone. But, those of you annoyed by the thought of paying AT&T twice for 3G service (iPhone 4 & iPad) may find it interesting.
How To: Use iPhone 4 data plan with iPad 3G
Fortunately, there’s no jailbreaking or SIM unlocking required. However, you will need to:
1. Remove the microSIM from the iPhone and iPad
2. Not mix up the two microSIM trays which are not identical
3. Change the iPad 3G’s APN (Access Point Name)
There is the chance that AT&T may detect what they consider to be unauthorized use of your iPhone 4 3G data plan on an iPad 3G. But, this seems highly unlikely. There’s also the little issue of being unable to make or receive voice calls on your iPhone 4 while it is SIM-less.
What we really need is a reasonably priced way to tether an iPad to the iPhone 4 over WiFi. AT&T’s iPhone tethering option does not provide a way to use it with an iPad wirelessly or otherwise.