If you have the official firmware 3.0 for the iPod Touch/iPhone it is possible to jailbreak, though it will be less complicated when QuickPwn comes out. For now, this method is the working alternative.
1. First, open iTunes, and shift+click on the "restore" button and upgrade yourself to the 3.0 firmware (even if you already have it).
2. Set it up as a new iPod/iPhone in iTunes.
3. It should work on the 3.0 firmware, un-jailbroken as of now.
4. Open "redsn0w" and browse for the firmware.
5. Click "Next".
6. Only check Cydia, not Icy.
7. Plug in the device, then turn it off.
8. Follow the instructions for putting it into DFU mode (power button for 3 seconds, both buttons for 10 seconds, only home button for 30 seconds). It will do the rest.
9. When it turns on again, you should have a normal iPod/iPhone with Cydia installed. It is successfully jailbroken.
Disclaimer: Know that I'm not responsible for any damages encountered to your device.