Earlier quoted context omitted.
In your tutorial you recommend rendering charts on OS X in order to get proper antialiasing. Isn't it easier to render to a vector format and then batch rasterize outside R with e.g. ImageMagick? Or even better, just use the vector format?
That workflow is neither the most user-friendly nor the most web-friendly. SVGs don't have the same flexibility and compatibility as PNGs yet, unfortunately.
On Windows, use ggsave, or if not using ggplot2, use Cairo. Linux's png output device has antialiasing.