you mean the Web GUI is only in the Nightlies, or the whole functionality?
smart playlists are done completely differently between 0.2.4 and nightlies. In 0.2.4, they are created through the playlist file. Look at the playlist file in the contrib directory for documentation and examples about how to use it.
In nightlies, the smart playlists are managed through the web interface. See the documentation linked from thew wiki for details on that.
Whats about normal playlist? Can I organize my own directory tree and this are the playlists then? That would be great If I want to copy some playlists fast on my notebook!
Either version will use .m3u style playlists. Make sure you have “process_m3u” set to 1 in your config file.