This jailbreak table should help you. Find your device and your firmware and click the links in the box for the jailbreak software and guides that should work for you. Note that RED means not yet done. GREEN means is done and working. No color change means that the jailbreak works, but may not be optimal or may not work in all cases. The guides should have more details. The green is the recommended solution for you.

Firmwares* iPod FW iPhone FW	iPhone 4	iPhone 3GS	iPhone 3G	iPhone 2G	iPad	iPod 3rd Gen	iPod 2nd Gen
4.0.2	Not Yet	Not Yet	Redsn0w 0.9.5b5-3 or newer Unlocked	Does Not Exist	Does Not Exist	Not Yet	Not Yet
4.2.1	Green Poison RC5 or Newer, no unlock	Green Poison RC5 or Newer, no unlock great for older bootrom , unlock with redsn0w / ultrasn0w.	Redsn0w 0.9.6b4 or newer, unlock with redsn0w / ultrasn0w	Does Not Exist	GreenPois0n RC5or newer	GreenPois0n RC5or newer	GreenPois0n RC5or newer
4.0.2-4.1	Green Pois0n (4.1 only) or Limera1n	Green Pois0n (4.1 only) or Limera1n	Redsn0w 0.9.6b1 or newer No unlock yet.	Does Not Exist	Does Not Exist	Green Pois0n (4.1 only) or Limera1n	Redsn0w 0.9.6b1 or newer MC models, use ipod touch 3g instructions
4.0-4.0.1	Jailbroken - Jailbreakme 2	Jailbroken - Jailbreakme 2 JB with stipulations: 1) Must already be pwned 2) Unofficial pwnage only Download here, use pwnage guide for help. Or use premade custom 4.0.1 firmware (google it). Recommend wait for official version. Unlocked	Jailbroken - Jailbreakme 2 Unlocked	Does Not Exist	Does Not Exist. See 3.2.1	Jailbroken - Jailbreakme 2	Jailbroken - Jailbreakme 2
3.2-3.2.1	Does Not Exist	Does Not Exist	Does Not Exist	Does Not Exist	Jailbroken - Jailbreakme 2	Does Not Exist	Does Not Exist
3.1.3	Does Not Exist	Jailbroken - Spirit / Redsn0w v0.9.4 / Pwnage Unlocked	Jailbroken + Unlocked - Spirit / Redsn0w v0.9.4 / Pwnage	Jailbroken + Unlocked - Spirit / Redsn0w v0.9.4 / Pwnage	Does Not Exist	Jailbroken - Spirit	Jailbroken - Spirit
3.1.2	Does Not Exist	Jailbroken + Unlocked - Spirit / Redsn0w v0.9.4 / Pwnage / Blackra1n	Jailbroken + Unlocked - Spirit / Redsn0w v0.9.4 / Pwnage / Blackra1n	Jailbroken + Unlocked - Spirit / Redsn0w v0.9.4 / Pwnage / Blackra1n	Does Not Exist	Jailbroken - Spirit / Redsn0w v0.9.4 / Blackra1n	Jailbroken - Spirit / Redsn0w v0.9.4 / Pwnage / Blackra1n
3.1	Does Not Exist	Jailbroken + Unlocked  / Pwnage	Jailbroken + Unlocked / Pwnage	Jailbroken + Unlocked / Pwnage	Does Not Exist	Jailbroken / Pwnage	Jailbroken / Pwnage
3.0.1	Does Not Exist	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Does Not Exist	Jailbroken - Redsn0w v0.8	Jailbroken - Redsn0w v0.8 / Pwnage
3.0	Does Not Exist	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Jailbroken + Unlocked - Redsn0w v0.8 / Pwnage	Does Not Exist	Jailbroken - Redsn0w v0.8	Jailbroken - Redsn0w v0.8 / Pwnage
2.2.1	Does Not Exist	Does Not Exist	Jailbroken + Unlocked - Quickpwn / Pwnage	Jailbroken + Unlocked - Quickpwn / Pwnage	Does Not Exist	Does Not Exist	Jailbroken - Obsolete. Update