This paper was officially published in The R Journal, 5/1, June 2013 [pdf]. A preprint in a somewhat nicer two column style is available from arxiv.org: http://arxiv.org/abs/1303.2140.
This paper was written for the two-column layout, but was published in The R Journal in a one column layout. To get the one-column layout, rename the following files:
RJwrapper.tex.onecol
->RJwrapper.tex
RJournal.sty.onecol
->RJournal.sty