First, you have the maps
, mapproj
and maptools
packages, that give you a wide variety of map functions, projections, and so on to create about any map you can think of.
Then there is the sp
package, which -among other things- allows you to plot any kind of data you load from the GADM database.
But most of all, there is the spatial projects page of R which gives you a whole lot more information, including links to mailing lists, to get going with R and spatial data. And if that's not enough, you have the CRAN Task View page for spatial data, listing 100+ packages to do what you want to do.
Think you had it now? There is more! Both books for sale and free blogs can help you finding out how to do what you want to do. And if you have some specific question, you can always come to StackOverflow , or use any of the mailing lists to get some more help.
So you see : This is R. There is no if. Only how. (Simon Blomberg)
powered by googling.