The NEWS entry is below; a number of these changes were already in the preceding 0.2.27 release of RcppArmadillo which was base on the beta for Armadillo 2.2.0.
CRANberries provides a diffstat report for 0.2.28 relative to 0.2.27. 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.0.2.28 2011-08-02 o Upgraded to Armadillo release 2.2.1 "Blue Skies Debauchery" * faster multiplication of small matrices * faster trans() * faster handling of submatrices by norm() * added economical singular value decomposition: svd_thin() * added circ_toeplitz() * added .is_colvec() & .is_rowvec() * fixes for handling of complex numbers by cov(), cor(), running_stat_vec