I actually sort of did this (but I cut them w/ a CNC router rather than 3D printing them).
https://imgur.com/a/fMy19 is the finished product; http://www.thingiverse.com/thing:1524543 are the files I generated and used. They aren't truly accurate maps -- they do have the elevation exaggerated to be more visually interesting, but it's consistently scaled. Some people have gone on to print them w/ 3d printers (rumor is they're on the wall at Makerbot now).
https://imgur.com/a/fMy19 is the finished product; http://www.thingiverse.com/thing:1524543 are the files I generated and used. They aren't truly accurate maps -- they do have the elevation exaggerated to be more visually interesting, but it's consistently scaled. Some people have gone on to print them w/ 3d printers (rumor is they're on the wall at Makerbot now).