We have some great news for those of you with an iPhone 3GS, as a new jailbreak tool has been released for iOS 4.1. Sn0wbreeze is back, and version 2.0.1 can jailbreak your device right now.
As reported from RedmondPie, Sn0wbreeze 2.0.1 supports a collection of iOS devices, but the 3GS sticks out as it allows you to jailbreak your device with the new bootrom. You can jailbreak the 3GS on the old bootrom, but RedmondPie states that you must be already jailbroken if you want to enjoy custom firmwares on Sn0wbreeze 2.0.
If you are willing to give this a go, you will find a full set of steps and instructions over at RedmondPie. The process seems quite complicated so you should only attempt this if you have previous jailbreaking experience.
If you are trying this out for the first time, obviously it goes without saying that doing so will void your warranty with Apple, so perform at your own risk.