..don't know if this helps anyone, but I was having the same problems with the album art not syncing to my 4S, seems if u manually select the albums art and copy it to your clipboard then select the album which is missing the album art in your itunes on your iPhone and paste it (and this is the important part) TWICE!! yes, twice, is at seems to add the album art to all the songs in the album. Save you going through every song manually as I was doing before. 