I haven’t bought Batman: Arkham City yet, but after seeing this Nightwing DLC im going to have to.  Dick Grayson, AKA Nightwing, will be a playable character in all challenge mode maps and will come with his own gadgets and special moves. The downloadable content which is due out on November 1st, will also come with 2 new challenge maps:  Wayne Manor and Main Hall.  Unfortunately, it will all come at a price of 560 Microsoft Points for XBLA and PSN $6.99.