A Armadillo release 3.900.0 was
provided by Conrad yesterday. It has been rolled into a new
RcppArmadillo
release 0.3.900.0 which is now on CRAN and in
Debian.

It has a number of nice changes, mostly on the performance side of things
(see below) and a minor cleanup/improvement in our Kalman filter example
(which, as I just realized, I forgot to note in the \code{NEWS.Rd} in the
released tarball):

Changes in RcppArmadillo version 0.3.900 (2013-06-04)

• Upgraded to Armadillo release Version 3.900.0 (Bavarian Sunflower)

  • added automatic SSE2 vectorisation of elementary expressions
    (eg. matrix addition) when using GCC 4.7+ with -O3 optimisation

  • added support for saving & loading of cubes in HDF5 format,
    contributed by Szabolcs Horvat

  • faster median(), contributed by Ruslan Shestopalyuk

  • faster handling of compound expressions with transposes of
    submatrix rows

  • faster handling of compound expressions with transposes of
    complex vectors

• Kalman filter example switched from inline to \code{sourceCpp},
  which simplifies / streamlines the C++ side a little

Courtesy of CRANberries, there
is also a diffstat report for the
most recent release
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.