Courtesy of CRANberries, there is also a diffstat report for 0.3.4.2 relative to 0.3.4.1 As always, more detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page.
Changes in RcppArmadillo version 0.3.4.2 (2012-09-25)
Upgraded to Armadillo release 3.4.2
minor fixes for handling sparse submatrix views
minor speedups for sparse matrices