I am wanting to create a program that everytime I run it, it gets the current playing tune in iTunes, and sets this as my Facebook status:

"I'm listening to current_playing_song, corrent_artist."

I have no idea how to start.
can someone suggest how?

Facebook has its own API, googles appengine wouldn't be the right way to go in my opinion. You're gonna need a program running on the users computer that will submit the status, because browser scripts cannot do this without exploiting some sort of flaw(which isn't good). I think you should look into urllib2, you can use that to post a status on facebook without using appengine or facebooks API, should be fairly simple. As for fetching iTunes current song, I have no idea, I'd assume theres an exposed API.