In fact the arm can be remotely controlled. As of 2005[1] ground controllers can uplink sequences of commands for the arm to complete. According to an article[2] about this Dragon launch, DEXTRE (two-armed human-like remote manipulator) will be remotely commanded to unpack cargo from the Dragon's unpressurized trunk and mount it on the station. I believe this is not a new thing at all.
[1]: http://www.space.com/1033-remote-access-canadarm-2-hand-grou...
[2]: http://spaceflightnow.com/falcon9/013/140923arrival/#.VCHgLy...