Myeah, indeed don't think there's a way you can actually transfer the Spotify playlists straight onto the iTunes unfortunately.
But you can go the recording route and use some Spotify recorder or something to save mp3 from Spotify and get them onto iTunes.
There's some Audials piece of software I used for the job a while back, works surprisingly good as a Spotify Recorder to record and convert Spotify to mp3 for my crappy ole mp3 player.
Suppose u should take look at it for your little problem, there's some guide on it:
http://audials.com/en...t_radios/spotify.html