Jailbreaking is for iPod touch, it basically reformats alot of shit, breaking the bond that apple gives it so you can customize it. Themes, free stuff, just overall cool stuff.

I updated mine to 4.0 the shall bring out the jailbreak for it… And I gotta admit that it rocks, also that's a game the designer of tb wii made:
http://fullyillustrated.com
http://www.superturboactionpig.com/