The BBC Press office has released the synopsis and casting details for the DT eps of SJA, and oh, are they spoilery!
Linkie here if you want to take a look (Warning for MASSIVE SPOILERS for the SJA eps within!):
http://tinyurl.com/ybogopbAnd here, at the Press Office homepage:
http://www.bbc.co.uk/pressoffice/proginfo/tv/2009/wk43/fri.shtml There's still no word on a Waters of Mars airdate, but we should know next week if it will be airing on Halloween, at least.