For those of you who are on AT&T, in order to get tethering on 3.1.3, the only current option is to jailbreak, and then installing MyWi. The IPCC tethering hack will not currently work on 3.1.3. Hopefully a future version of redsn0w will address this.
Anyway, if you want to jailbreak, below are some instructions I typed up for 3G users (modified from RedmondPie and a few other places), to make it easy. You can obviously also jailbreak a 3GS, but not using these instructions. Also, keep in mind, there currently isn’t a publicly available unlock for 3.1.3 (for those needing to use it on non-AT&T networks), so I’d suggest NOT updating to it. If on a version prior to 3.1.2, you can update to 3.1.2 and follow the instructions below. (more…)