Got an Edge last week.  I have a 40G 4th Gen iPod click wheel and purchase songs through iTunes.  Initially, SYNC wouldn't play any of the songs I purchased through iTunes, but I was able to solve this problem by converting all my songs from m4p to m4a files.  I then updated all my playlists with the new files, but SYNC still won't recongnize any playlists.  Everything else works fine.  Anyone have a similar experience or know a solution?  Thanks!