Thanks to the efforts of the good folks at the Electronic Frontier Foundation, it’s now official: you can do what you want with your own devices.
Apple argued in this jailbreaking case that copyright law prevents people from installing unapproved programs on iPhones. But the EFF successfully argued that making a phone interoperable amounts to fair use. Copyright law says that if you pay for something, you have the right to use it as you wish as long it is not for some kind of commercial benefit.
The ruling also applied to video remixing, so is it possible we’ll see the return of all those great Hitler parodies spun out of Downfall?