I want that map, is it an updated one?
That look like the same map that shows up in the Supercharger event video on the events page of this website. I understand that the exact location of the dots should not be take too seriously, but it likely does show what major highways they will cover.
The map was from the supercharger launch event. See http://www.youtube.com/watch?v=wgk5-eB9oTY, beginning at about 5:47. Note that the maps are only illustrative, and do not reveal actual locations of proposed superchargers. The only update I am aware of is the announcement of several superchargers on the east coast.
I hope they put a few more along I-70. What is shown would not accommodate a cross country trip. For instance, Denver to Kansas City is 605 miles with no chargers shown between these cities. I-80 and I-40 look pretty good.
The map posted by Eleonor2002 is a two-year map. Take a look at the 4-5 year map, beginning at about 6:00 on the video I posted. It is much more extensive. Of course we hope TM thrives over the next few years so that this plan can become a reality.
Here is the short (2 yr) and long term Supercharger map on TeslaMotorClub forum. CHeck it out: