However, some clever folks have figured out a way to enable tethering on iPhone OS 3.0 without the need to jailbreak their iPhone.
There are several methods floating around to enable tethering on iPhone OS 3.0 but I found the method where you can enable it via iPhone's Safari, the easiest.
The process of tethering allows your laptop to use your iPhone's data connection to surf the internet.
The idea behind the hack to enable tethering on the iPhone running iPhone OS 3.0 is to download a .ipcc, which is carrier specific and update your iPhone with it via iTunes. The procedure gets even simpler using iPhone's Safari browser.
Folks at BenM.at have hosted several iPhone tethering configuration files for many carriers across several countries. You need to go to the following link http://help.benm.at/help.php using iPhone's Safari browser.
Then click on Mobileconfigs on that page:
Select your country from the list.
Once you have selected the country, you will be prompted to select the provider.
Tap on the Install button.
Then tap on the Install Now button.
Tap on the Done button.
That's all, it is as easy as that and no hacking required, can you believe it and the best part is it's free.
But the way this hack has spread, I won't be surprised if AT&T clamps down on it soon so enjoy it till it works.
Please note that this is a hack so proceed with caution.
Some known issues:
This seems to disable Voicemail feature for some users.
It doesn't seem to work with 1st generation iPhone.
iPhone OS 3.1 Beta 2 disables the tethering functionality enabled using this hack, so don't upgrade to iPhone OS 3.1 whenever it is released if you want to use this functionality.
As always, please don't forget to tell us how it goes.