Ipad:
3.2.2: Redsn0w
3.2.1: Redsn0w
(More coming soon!)
Iphone/Ipod touch:
3.1.2: Blackra1n
2.2.1: Blackra1n
2.2.2: Blackra1n
4.0: Greenp0ison or Redsn0w or jailbreak me
3.1.3: Blackra1n or limera1n
4.1: Pwnage tool or Greenp0ison or Redsn0w or limera1n or jailbreak me
4.2: Redsn0w or Greenp0ison or pwnage tool or limera1n or jailbreak me
4.2.1: Redsn0w or Greenp0ison or pwnage tool or limera1n
2.2: Yellow Ra1n + (unknown)
Other specific jailbreaks: pinkra1n, sn0wbreeze, bluera1n, other +++
Ipod Nano:
(coming soon)
Apple tv:
Specific jailbreaks: Jailbreak me or Redsn0w (i think they work for all firmwares)
More coming soon! see the iphone help page for more information on jailbreaking