Cre.ations.net posts a step-by-step guide on how to tether your iPhone 3G to your laptop.
The process of tethering allows your laptop to use your iPhone's 3G internet connection, avoiding the need to find separate internet connectivity for your laptop. Tethering, of course, is against AT&T's terms of service and could result in penalties to your account. Strangely, AT&T does offer tethering as a $30-additional fee for other 3G smartphones. It's unclear if the absence of this feature on the iPhone is due to Apple's or AT&T's reluctance, but it certainly would require Apple to integrate software support if they were to offer it.
The process is broken down into these simple steps:
- Jailbreak your iPhone 3G
- Install 3Proxy and Terminal
- Create an ad-hoc Wi-fi network using your laptop
- Join the network with your iPhone
- Find the iPhone's IP address
- Open Terminal and run the proxy program
- Open Safari on your iPhone and open a web page
- Configure your browser to use the proxy
A more detailed guide can be found at Cre.ations.net.