A friend of mine is a writer and big Who fan and anyway to cut a long story short he just did an interview with Steven Moffat (he also has done an interview with Arthur Darvill, and has a Matt Smith one coming up). It's pretty much spoiler free but a very interesting read, and the question regarding a possible return by Captain Jack was my suggestion 
http://citysearch.com.au/tvguide/1137872979970/Doctor+Who's+Head+Writer+an+Impossible+Tease

http://citysearch.com.au/tvguide/1137872979970/Doctor+Who's+Head+Writer+an+Impossible+Tease