The LimeWire playlist in iTunes right? You didn't mention iTunes but I'm guessing this is what you're talking about. This playlist simply reflects what's in the LW downld folder. It can be played but not burnt or copied.

If you're refering to playlists saved via the LW media player, then that can work in iTunes or any other player that supports that type of playlist format. But playlist files only work if the original files are still in their original location. Since a playlist is simply a pointer; it points the player to where the songs are.