Rcpp 0.8.9 was pushed to CRAN recently. Apart from minor bug fixes, this release concentrates on modules, with lots of new features to expose C++ functions and classes through R reference classes.

The Rcpp-modules vignette has all the details

The major points are highlighted in the NEWS entry below:

0.8.9   2010-11-28 (or even -27)

    o   Many improvements were made to in 'Rcpp modules':

        - exposing multiple constructors

        - overloaded methods

        - self-documentation of classes, methods, constructors, fields and 
          functions.

        - new R function "populate" to facilitate working with modules in 
          packages. 

        - formal argument specification of functions.

        - updated support for Rcpp.package.skeleton.

        - constructors can now take many more arguments.
        
    o   The 'Rcpp-modules' vignette was updated as well and describe many
        of the new features

    o   New template class Rcpp::SubMatrix and support syntax in Matrix
        to extract a submatrix: 
        
           NumericMatrix x = ... ;
        
           // extract the first three columns
           SubMatrix y = x( _ , Range(0,2) ) ; 
        
           // extract the first three rows
           SubMatrix y = x( Range(0,2), _ ) ; 
        
           // extract the top 3x3 sub matrix
           SubMatrix y = x( Range(0,2), Range(0,2) ) ; 

    o   Reference Classes no longer require a default constructor for
        subclasses of C++ classes    

    o   Consistently revert to using backticks rather than shell expansion
        to compute library file location when building packages against Rcpp
    on the default platforms; this has been applied to internal test
        packages as well as CRAN/BioC packages using Rcpp