I think we've seen with Apple that, once again, they have created a truly transformational product in the iPhone. It transforms the user experience, in that people think of it differently than they do, say, a Nokia phone. It's no longer a phone, it's an iPhone--and the connection with it and the way it connects to users' lives is radically different.
See Alan Cooper's keynote from interactions '08: here
I'm sure we can think of others as well, but the iPhone is definitely transforming how people communicate, and how they think about their communication devices.