Version 0.7.8 of Rcpp, released just a few days ago contained a nasty bug or two which we noticed when trying to built the initial release of RcppArmadillo on 64-bit platforms.
The full NEWS entry for this release follows:
0.7.9 2010-03-12 o Another small improvement to Windows build flags o bugfix on 64 bit platforms. The traits classes (wrap_type_traits, etc) used size_t when they needed to actually use unsigned int o fixed pre gcc 4.3 compatibility. The trait class that was used to identify if a type is convertible to another had too many false positives on pre gcc 4.3 (no tr1 or c++0x features). fixed by implementing the section 2.7 of "Modern C++ Design" book.
As always, even fuller details are in Rcpp Changelog page and the Rcpp page which also leads to the downloads, the browseable doxygen docs and zip files of doxygen output for the standard formats. A local directory has source and documentation too. Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page
Update: First version number corrected to 0.7.8.