Lost your tethering ability since the update to 3.1.2? Here’s the quick fix. You’re already jailbroken, right? Head on over to Cydia and install the MyWi app. Its going to install the Rock app also (don’t worry if you don’t want Rock, tis only temporary).
Launch the Rock app, you will need to create a Rock ID, but it only takes a second. And now there will be an update to the MyWi app….run it. It will prompt you to a “soft restart” or a re-spring. Open MyWi and turn USB/Bluetooth tethering on. Now reboot the phone. After the restart, go to Settings–General–Network–Internet Tethering. Yay! Easy huh? Now about Rock and MyWi.
Rock doesn’t always play nice with Cydia, and MyWi is a paid app. So you can keep them, pay the $9.99 for MyWi and support their future development, or SSH in and delete them. Then re-spring. Now all this is working on my Mac. Even after a re-boot. I’m not sure on Windows, so let us know in the comments.