The process is quite involved and not for the mild-mannered. Not only is "tethering" against AT&Ts terms and conditions, you also have to "jailbreak" your iPhone. In a nutshell, here's the basic procedure:
- 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 explanation can be found at the cre.ations.net website. Follow this link for the lowdown.
Nice post. Seems pretty simple actually. I'll probably put a how-to video on my site(http://www.iPhoneNewsVault.com)