With this release, the older API which we have been referring to as the classic Rcpp API has been split off into its own new package RcppClassic to ensure backwards compatibility. Rcpp will now contain only the new API.
We also fixes a number a minor bugs and applied a few contributed patches which extended functionality or documentation as detailed below in the NEWS entry:
0.9.0 2010-12-19 o The classic API was factored out into its own package RcppClassic which is released concurrently with this version. o If an object is created but not initialized, attempting to use it now gives a more sensible error message (by forwarding an Rcpp::not_initialized exception to R). o SubMatrix fixed, and Matrix types now have a nested ::Sub typedef. o New unexported function SHLIB() to aid in creating a shared library on the command-line or in Makefile (similar to CxxFlags() / LdFlags()). o Module gets a seven-argument ctor thanks to a patch from Tama Ma. o The (still incomplete) QuickRef vignette has grown thanks to a patch by Christian Gunning. o Added a sprintf template intended for logging and error messages. o Date::getYear() corrected (where addition of 1900 was not called for); corresponding change in constructor from three ints made as well. o Date() and Datetime() constructors from string received a missing conversion to int and double following strptime. The default format string for the Datetime() strptime call was also corrected. o A few minor fixes throughout, see ChangeLog.Thanks to CRANberries, there is also a diff to the previous release 0.8.9.
As always, even fuller details are on the 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