Conrad Sanderson made the official 2.4.0 release of Armadillo last evening. This was wrapped into RcppArmadillo release 0.2.32 which arrived on CRAN earlier today.

The NEWS entries summarising the changes since the 2.2.* series, we already saw most of this with the two prerelease 0.2.30 and 0.2.31:

0.2.32  2011-12-04

    o   Upgraded to Armadillo test release 2.4.0 "Loco Lounge Lizard"

    o   Minimal changes relative to 0.2.31 based on 2.3.92, next section is
        relative to the previous stable release series 2.2.* of Armadillo

          * added shorter forms of transposes: .t() and .st()
          * added optional use of 64 bit indices, allowing matrices to have
            more than 4 billion elements 
          * added experimental support for C++11 initialiser lists
          * faster pinv()
          * faster inplace transpose
          * faster handling of expressions with diagonal views
          * fixes for handling expressions with aliasing and submatrices
          * fixes for linking on Ubuntu and Debian systems
          * fixes for inconsistencies in interactions between matrices and
            cubes 
          * refactored code to eliminate warnings when using the Clang C++
            compiler 
          * .print_trans() and .raw_print_trans() are deprecated

Courtesy of CRANberries, there is also a diffstat reports for 0.2.32 relative to 0.2.31 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.