Firmware 3.0.1 jailbreak

Good news is that you can still use redsn0w 0.8 to jailbreak firmware 3.0.1. Here's the step-by-step plan:

1. Download both firmware 3.0 and firmware 3.0.1 (link).
2. Download redsn0w 0.8 (link).
3. Update or restore to official 3.0.1 in iTunes.
4. Run redsn0w.
5. When redsn0w asks you to identify the IPSW used, point it at the 3.0 IPSW instead of the 3.0.1 one.
6. Follow the instructions.
7. After the jailbreak, reinstall ultrasn0w 0.9 if you need the unlock.