geomnet is a package built on top of the most recent major ggplot2 release. It provides a ggplot2 geom called geom_net to visualize graphs and networks. It also include the function stat_net to calculate network layouts with the sna package. Finally, the function geom_circle is included to draw circles using ggplot2.
You can now install geomnet directly from CRAN.
install.packages('geomnet')
There are many usage examples in ?geomnet::geom_net.
Enjoy!