We have already done a detailed step by step guide on how to jailbreak iOS 4.1 on iPhone 4 and iPhone 3GS. The same instructions applies to the iPod touches as well. All you have to do is to upgrade your iPod touch 4G or iPod touch 3G to the latest iOS 4.1 firmware (download link given below), and then follow the step by step guide posted here to Jailbreak the said devices on iOS 4.1 using Limera1n.
You can also alternatively follow the step by step guide for jailbreaking iOS 4.1 using Limera1n in the video embedded below.
UPDATE 1: Our complete step by step guide on how-to jailbreak iPhone 4 and iPhone 3GS on iOS 4.1 using Limera1n can be found here.
UPDATE 2: Follow the step by step instructions posted here to jailbreak iPad on iOS 3.2.2 using Limera1n.