See Boost.Extension at http://boost-extension.blogspot.com/

The library is under development but basically works as far as I can tell.

If you try out Boost.Extension, feel free to send me any questions or problems. It has been tested recently on VC 2008, VC 2005, GCC 3.4 and 4.0 on Linux and GCC 4 on OS X. As such, it can handle .dll, .so, .dylib, .bundle and their equivalents.

The documentation should be relatively complete, though I'm working on replacing the examples with some better ones. It's available in the Sandbox:

svn.boost.org

The directories are: sandbox/libs/extension and sandbox/boost/extension.

Jeremy Pack