Download the R package here.
The package will soon be available on the CRAN.

A model based clustering method for clustering the nodes of a graph according to a similar connectivity behaviour. The model allows the vertices to belong to multiple clusters, and, to some extent, generalizes the well known Stochastic BlockModel.
Full description of the method may be found here:
Overlapping Stochastic Block Models with Application to the French Political Blogosphere
Latouche, P. and Birmelé, E. and Ambroise, C.
Annals of Applied Statistics Vol. 5 No. 1 pp. 309-336, 2012.