http://lesswrong.com/r/discussion/lw/npy/are_smart_contracts_aicomplete/

(spoiler: "yep, looks like it." Though the comment that says "let's not call them contracts to avoid confusion with the legal version" rather misses the point that smart contracts are specifically hyped as a replacement for legal contracts, and also note the downvotes for people being so rude as to point out you don't get to exempt yourself from the law just by saying so.)