The realistic answer is that data over power, may or may not be possible, but it would be a HUGE infrastructure undertaking and isn't likely to happen anytime in the near future.
Broadband over Power is actually being built out in some areas, and in some places it's being used as a sort of first step toward Smart Grid (with the obvious advantage of providing some nice revenue enhancement). The problems are that (a) nobody really wants to invest in broadband infrastructure right now, since it's not really the hot market it was ten years ago; and (b) it generates an enormous amount of radio interference and a lot of related headaches for the power company.
Smart Grid (which is, for the most part, a totally separate thing) is already rolling out in some places, a little at a time. (Look around sometime for power poles with little antennas on top of them; most are repeaters, our first local steps into Smart Grid.) It's not going to deliver huge or impressive results quickly, no, but it does provide more local results, like the ability to monitor and control the system remotely rather than having to send out switchmen every time. That cuts outage time.
Biggest problem right now, other than funding the thing, is defining it. We're dangerously close to letting people call any damn thing part of the "Smart Grid." We could get some joker painting the transformers purple and saying they're Smart, and it's a little hard to show it's not. But it's getting there.