Arkham City DLC set for Dec 20

Iceberg Lounge location will be included as a challenge map, The Iceberg

According to Batman Arkham City's official Twitter page, new challenge maps will be released as DLC on Dec 20 2012, just in time for Christmas.

The DLC will include three new maps, Batcave, Joker's Carnival and The Iceberg.  These maps may sound familiar since all three maps were available as pre-order bonuses from various retailers (for instance I received the Joker's Carnival Challenge Pack for pre-ordering with GameStop).  Curious to see how they price this considering many of us would be paying for a map we already own.