Apple will reveal iPhone 4.0 operating system on Thursday, April 8. Can you jailbreak iPod touch 4.0? You can definitely jailbreak iPod touch 4.0 with the iPod touch first generation, and iPod touch second generation, but the iPod touch third generation will probably be tethered (which means you will need to jailbreak it again every time you reboot your iPod touch).
A hacker named comex, recently discovered an iPad jailbreak, which is untethered and works on iPod touch and iPhone as well but won’t be releasing it until iPad 3G is out. If the iPad jailbreak is released before iPhone OS 4.0, Apple has enough time to patch the exploit and force iPod touch third generation users to have a tethered jailbreak instead of an untethered on. For now, you can download iPhone toolbar (works on Firefox, Internet Explorer, or Safari) to receive instant updates on when the jailbreak is released.
-- Post From My iPhone2g