How to Tether an iPhone to a Laptop Using PdaNet Software
Apple officially does not allow the tethering of an iPhone to a Laptop or PC so the laptop can use the 3G connection for connecting to the Internet. Fortunately, you can get around this restriction by "jailbreaking" your phone and installing the PdaNet app. Here's the step-by-step process for tethering an iPhone to a laptop.
Step 1: Have a Jailbroken iPhone with iOS 3.1 or later. Mine happens to be 3.1.3
Step 2: Use the Cydia app on your phone ot download an app called "PdaNet". Just do a search for it.
Step 3: You can either tether between your phone and laptop using wifi or through the USB cable. I find the USB option to be a bit faster personally and is less susceptible to problems. You do need software to run on your Mac or PC however. You can download the PdaNet client software for Windows, or Mac OS X here:
Step 4: Connect your iPhone to your PC or MAC using the iPhone USB cable.
Step 5: Launch the PdaNet app on your iPhone. Go into the "Settings" section and check the "USB Mode" setting.
Step 6: On your Mac or PC, launch the PdaNet client application and choose "Connect". It will take a few seconds but your iPhone screen should eventually display "Connected" and begin counting the KB in and out.
You will now be connected and can use your laptop to surf the web, check email and even VPN.
Keep in mind that PdaNet is only free for 14 days. After that point the free edition will "start blocking secure web sites (web sites that require login)". You can upgrade to the paid version with a $29 PayPal payment.
That's all there is to it. You can now use your tethered iPhone to laptop Internet connection anywhere you have Edge or 3G coverage.