I came across this page via the chloropleth challenge page. I've not yet understood all of the code above, but as you surely put a lot of effort into the challenge, I'd still like to ask you one question:
In the meantime, have you found one package that was particularly useful for displaying (and generally working with) maps in R? Or have you spent more time on developping your own maps-related projects?
I'm asking because I'd like to work with maps in the near future and I'm still not sure which package to use.