Ok, I've been looking around for some more information on this and found quite alot, firstly it is offical that the game will be released in Fall 2011 http://www.batmanarkhamcity.com/uk/index.html
Now this is my favourite thing I found,
Batman: Arkham City has been revealed. Here are all of the leaked details on Rocksteady's massive sequel in one place.
1. Two-Face and Catwoman
Two-Face and Catwoman are in the game, and their character models are looking superb. We can assume there will be a ton of coin-flipping schizophrenia and troubled romance. Meow. It has been revealed that Two-Face looks to murder Catwoman to earn himself some kudos with the other inmates.
2. Arkham City
Arkham City is in fact an annexed section of the Gotham's slums, which has been walled in to contain all of the city's craziest and deranged criminals. Created by the newly-elected Mayor Sharp, the district is governed by security group Tyger. The only villain not resurfacing within this den of hostility is the Joker, who continues to hide after his Titan overdose. It's been revealed that he is very sick.
3. Gang Warfare?
Criminal gangs will play a part in the plot, with each group controlling certain districts of Arkham City. The Riddler's mob will be in there, depicted on Batman's detective vision in a green tinge, which seems to nod to some kind of faction element.
4. Zsasz Returns
Psycopathic murderer Zsasz will return, this time contacting Batman periodically from pay phones with side-quests and brutal interrogations that fill in for The Riddler's puzzles. Achievements and trophies will undoubtedly be attached to these tasks. Does this mean the Riddler will be a full villain rather than a puzzle device?
5. Bang! Pow! Crash!
Batman's combat receives an upgrade, allowing him to counter two moves at once, giving him an edge over new gun-wielding enemies. It's also a good thing Batman can now counter projectiles. Batman can even call upon gadgets mid-battle, letting him spray explosive gel on the backs of enemies to turn them into walking bombs. He also has a cape swipe that stuns enemies.
6. Power Up
Batman: Arkham City will avoid the common pitfall of sequels and let you use all of the skills from Arkham Asylum at the start of the game. New confirmed gadgets include smoke bombs for stealthy escapes and blinding thugs.
7. Super Sleuth
There will be more puzzles and Batman's trademark forensic detective investigations. It has been revealed that Batman will be able to flex his sleuthing muscle like a CSI star, judging bullet trajectories and so on.
8. Alfred Gets Recognition
Batman receives backup from Alfred this time round rather than Oracle. Bruce Wayne's loyal aide can help him jack into police radio frequencies using his new broadcast analyser. Can we assume Oracle has been kidnapped?
9. The Boy Wonder
Robin could be in it. Yeah we know, that doesn't sound so good, but it has been revealed that a 'Flying Graysons' poster, the family trapeze group Batman's young ward once belonged to, has been spotted in Arkham City.
10. Co-op?
We've already mentioned that Two-Face is trying to kill Catwoman to gain respect within the criminal underworld, which makes her an enemy of Batman's enemies. There has been no talk of co-op so far, but the premise is well and truly there.
Somewhere in there it should explain why it is call Arkham City rather than Gotham City.
The information just doesn't stop so instead of pasting all of it on here, be sure to check this out!: http://www.gamesradar.com/xbox360/batman-arkham-city/news/batman-arkham-city-exposed-first-image-of-villains-plus-new-details-on-story-characters-and-gameplay/a-20100811102522728029/g-20091214174528870002/c-1#10374492282500184926147375512947157
