A listserv to which I subscribe is discussing mapping the transgenic crops in their regions and the lack of accessibility to the information that would allow plotting of those fields of GE canola, corn, soy and sugar beet.
Its not a new idea. An example is the proposal by a group of US Biologists for a national wide biotech map. In South Africa, a civil society group (through access to information legislation) produced a GMO Biohazard map (of field trials)
Australia has a GMO Finder
There is a fascinating collection of google hits for GE maps.
Here are a few that interested me:
litigation map for genetically engineered crops
GE map censored in France
GE free zones in Europe