VLC is the king of Open Source video programs. It supports tons of codecs and is loaded with features. What I have found is that there are no smart playlist files out there. Of course there are tons of playlists files such as M3U. But these playlists are only fixed playlists and not smart playlists. The only smart playlist file type I know of is WPL files which can only be used by Windows Media Player. Every media player for music and audio that supports smart playlists doesn't create a file for the smart playlist but saves then into the program themselves.
VLC should consider creating a open standard smart playlist that would work in VLC and can be made in VLC. I can see others developers in the future wanting to use VLC smart playlists into their own media players. This way people can backup their smart playlists, easily transfer them from device to device. The best way to achieve this is to use XML to structure the smart playlist file and add many features to it just like iTunes has.