Hopefully that will soon change thanks to Cumberbatch's casting (via The Playlist) in the upcoming (re)adaptation of John Le Carre's Tinker, Tailor, Soldier, Spy, written by Peter Morgan (The Queen, Frost/Nixon) and directed by Tomas Alfredson (Let The Right One In). He's yet another excellent addition to an already outstanding roster comprised of Gary Oldman, Ralph Fiennes, Colin Firth, Michael Fassbender and David Thewlis. He'll be playing Peter Guillam, the protege of Oldman's George Smiley, who helps to identify a Russian mole within the British intelligence community.
Alfredson's Tinker, Tailor isn't due until 2012, unfortunately, so if you'd like to catch Cumberbatch sooner, I'd highly, highly recommend checking him out in Sherlock, BBC's modernization of Sir. Arthur Conan Doyle's iconic detective. Not only does he make for a phenomenal Holmes (with a great Martin Freeman filling in as Watson), but the first episode of the series is by itself better than Guy Ritchie's big budget Hollywood reboot-- and that's saying something considering I actually enjoyed Ritchie's film.