Meet Karen Gillan, the new companion for Matt Smith's 11th Doctor
http://news.bbc.co.uk/1/hi/entertainment/8073734.stm
With no character name yet, I'm kinda hoping she's a young River Song (from the fourth season, "Silence in the Library" and "Forest of the Dead"), since it's been said she plays a major part in the Doctor's life in the future, and in her two premiere episodes (when played by Alex Kingston), she knew the Doctor's real name, which has always been something he's refused to tell even his most trusted past companions...