Looks like there won't be an extended version of the prom, but there will be extra scenes from this years prom shown on the red button and on iPlayer following the BBC3 repeat tomorrow (Thurs 21 Nov): http://www.bbc.co.uk/programmes/p01l1z04/profiles/dw50 Still no Song for 50... poor Murray Gold.
I hope this turns up on another source. I'm not gettign involved with iTunes just to watch the extra scenes. As for 50, jeez, talk about gettign swept under the rug. I hope it at least turns up in the Special. Yes, I didn't care for the lyrics, but the orchestration itself was quite nice.