RedSn0whas been very hot for the last few days. After releasing thebeta versionand testing it out for a while, the Dev Team officially releasedRedSn0w 0.9, which didn’t contain theIPCC tethering hackthat would allow tethering on iPhone OS 3.1.2.
It has now been fixed as the Dev Team updatedRedSn0w to 0.9.3, which now includes the IPCCtetheringhack. For those of you who have no idea what “IPCC tethering hack” means, here is moreinformation:

It allows you to install cellphone Carrier Bundles that aren’t officially signed by Apple. This lets you, for instance, install a Carrier Bundle that allows you to use your iPhone as a way to connect your PC to the internet (through your 3G cell connection). This hack is always installed on 3G and 3GS phones by redsn0w 0.9.3 (no selection is required). It isn’t included at all in 0.9.2 (it’s still in a trial phase). Note that carriers may not like you tethering behind their back so you do so at your own risk.
So by jailbreaking your iPhone usingRedSn0w0.9.3, you will automatically get the base for iPhone tethering, but you will still have to download the rightMobileConfigsfile from http://www.benm.at/help/help.php and install it, directly from your iPhone.
Note that this website has saved my butt many many times when traveling overseas. As a matter of fact, http://www.benm.at/help/help.php saved my butt just hours ago. I am currently in Thailand and the mobile carrier I am using doesn’t allow tethering. I quickly visited BenM.at and downloaded the right MobileConfigs file, which allows me to write this article you are currently reading by tethering my iPhone (aka using my iPhone as a modem).
To get the tethering hack, you will have to jailbreak your iPhone using RedSn0w 0.9.3. It is available for download fromhereand here is myRedSn0w tutorial. For the latest information about RedSn0w, please check outthis page.