The second paper is Eddelbuettel and Sanderson (2013). This one is titled RcppArmadillo: Accelerating R with high-performance C++ linear algebra and introduces the RcppArmadillo package which brings Conrad Sanderson's Armadillo C++ template library to GNU R by deploying Rcpp. The paper is currently "in press" at Computational Statistics & Data Analysis but the DOI 10.1016/j.csda.2013.02.005 will remain once a volume and issue is assigned by CSDA.
Preprints of both papers are available via my papers page, and as vignettes in the corresponding packages.
The upcoming Rcpp class in New York will feature Rcpp, RcppArmadillo and RcppEigen. Space is still available.