For certain setups of the map, basemap does not draw the coast-lines for Europe. See for example the "Draw great circle between NY and London" example on http://matplotlib.github.com/basemap/users/examples.html This seems to have been fixed in the current version 1.0.4, which is not yet available in portage: http://sourceforge.net/projects/matplotlib/files/matplotlib-toolkits/basemap-1.0.4/
+ 27 Jun 2012; Patrick Lauer <patrick@gentoo.org> +basemap-1.0.4.ebuild: + Bump for #423735