I've been spending some time lately reading about the "smart grid" and trying to understand what it means. The short answer seems to be that the smart grid is whatever you want it to be, with companies ranging from General Electric to Google each staking their claim to some part of this marriage of electricity transmission and IT. I intend to write a couple of posts about it and the companies involved. In the meantime, you might be interested in Google's recent announcement of home energy software for the delivery end of the grid.
For more information, the NYTimes Green Inc. blog tells the story better than I can.