After releasing PwnageTool bundle for iPad, Johnny Franks, the iPhone enthusiast and hacker has now released a bundle for jailbreaking iOS 4.3 on iPod touch 4G (fourth-gen). This bundle can be used with the current version 4.1.2 of PwnageTool to create custom firmware file to jailbreak the 4th-generation iPod touch.
Cydia is fully working on iOS 4.3 Beta firmware. Unfortunately though, this is a tethered jailbreak, which means you will need to restart your iPod touch in a tethered-jailbroken mode on every reboot.
Full complete step by step instructions on how to jailbreak iOS 4.3 can be found here.
NOTE: The jailbreaking procedure for iOS 4.3 is complex, and hence is meant for advanced users only. It will require you to make your own ramdisk because the latest official version of PwnageTool makes a broken one for iOS 4.3. Proceed at your own risk only. We are not to be held responsible if you end up bricking your iPod touch.