The short NEWS file extract follows:
0.2.6 2010-09-12 o Upgraded to Armadillo 0.9.70 "Subtropical Winter Safari" o arma::Mat, arma::Row and arma::Col get constructor that take vector or matrix sugar expressions. See the unit test "test.armadillo.sugar.ctor" and "test.armadillo.sugar.matrix.ctor" for examples.
More information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page.