Basically, the framework is there. All it will take is one overzealous nationalist, one religious extremist, or one extremely greedy, immoral, charismatic corporate puppet and their resources for evil are bigger than at any other time in history. Look at how well Hitler tracked Jews with basic 1940's punch card technology. Imagine if he had had access to the NSA databases of today. I apologize for going all Godwin's Law here, but it seems relevant.
What truly amazes me is how complacent we are about it as a society. 1984 was obviously popular for a reason, but when the set up for that book is staring us in the face, we don't even seem to blink. Maybe we'll be different when (not if) the abuses of this kind of power start happening...