Ever wondered if you could swap out the micro-SIM card in your iPhone 4 to get free data from AT&T on the iPad 3G? Well stop wondering. Turns out a simple change to APN settings on the iPad makes it possible to use the iPhone 4 data plan on Apple's tablet. No jailbreaking or SIM card modifications required.
As the helpful folks over at TUAW explain, the procedure is quite simple but does involve many small parts. Carefully use a SIM removal tool or paper clip to open the SIM trays on your iPhone 4 and iPad 3G. Don't mix up the trays and keep track of which card came from which device! When the iPhone 4 micro-SIM is safely inside the iPad 3G, all you need to do is make a change to the APN settings on the iPad.