Well, I guess it depends on what you're jailbreaking it for.
It can be stealing.
The process of jailbreaking itself does nothing in terms of stealing, or breaking the law. Hence jailbreaking is completely legal. the illegal part is where people have created apps that allow users to have cracked versions of apps. I don't want anyone talking about that here, becuase, well, they'll get banned. But the point is: jailbreaking is legal. You can look through the wikipedia article, which addresses legality I think.
I'll make another post with the tweaks I'm using. I just changed my setup again last night, but my springboard didn't change. I've just been messing with my lockscreen.