Are you interested in creating you own cross-platform application that uses plugins?
If that is the case, you can take a look at this:
http://www.shell.linux.se/edev/files/cbpluginhelp.zip (Sorry it's Dev-C++, but that was before i knew of Code::Blocks..)
It is a awfully slow and bad implementation of a plugin system, but it works

. It is designed to be cross-platform but only windows is implemented. To port it to posix, you should replace LoadLibrary with dlopen, FreeLibrary with dlclose and GetProcAddress with dlsym.
One important thing, that I have forgotten in this simple system, is that you will need to delete the plugin from the plugin dll, because the application and the plugin may use different memory allocation routines (if you compiled with another compiler, for example) otherwise you can get REALLY annoying errors.
/Per Eckerdal